3066 PXI Multi-way Active RF Combiner 250 MHz 6 GHz. User Manual

Transcription

1 3066 PXI Multi-way Active RF Combiner 250 MHz 6 GHz User Manual Document no /121 Issue 2 28 September 2015

2 PREFACE About this manual This manual explains how to set up and configure a Cobham 3066 PXI Multi-way Active RF Combiner. Where necessary, it refers you to the appropriate installation documents that are supplied with the module. Please note: this manual applies only when the instrument is used with the supplied software. This manual provides information about how to configure the module as a stand-alone device. However, one of the advantages of Cobham 3000 Series PXI modules is their ability to form versatile test instruments, when used with other such modules and running 3000 Series application software. Aeroflex Limited 2015 Longacres House Six Hills Way Stevenage SG1 2AN UK No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, or recorded by any information storage or retrieval system, without permission in writing by Aeroflex Limited (trading as Cobham Wireless and hereafter referred to throughout the document as Cobham ). 2

3 PREFACE Intended use Cobham 3000 Series PXI modules are intended for installation only in a PXI chassis approved by Cobham, or a Cobham instrument designed for that purpose. The 3066 module is designed to interface various PXI RF test resources with the item(s) under test. This manual is intended for first-time users, to provide familiarity with basic operation. Programming is not covered in this document but is documented fully in the help files that accompany the drivers and associated software on the CD-ROM. Driver version This PXI RF module is designed to be used with the driver software supplied with the module on the Cobham 3000 Series PXI Modules CD-ROM, part no /028. You can also download the latest driver from the Cobham website. Cobham makes every endeavor to ensure 3066 hardware remains backwards compatible with earlier versions of the module driver. However, operation with earlier versions of driver software may not be supported. is a registered trademark of Cobham plc, the parent company of Aeroflex Limited. PXI is a trademark of the PXI Systems Alliance. Windows is a registered trademark of Microsoft Corporation. 3

4 PREFACE Associated documentation The following documentation covers specific aspects of this equipment: If you want to Refer to Find information about soft front panels, drivers, application software, data sheets, installation, getting started and user manuals for this and other modules in the 3000 Series PXI Modules CD-ROM Part no /028 Supplied with the module Install modules into a rack, interconnect them, power up and install drivers PXI Modules Common Installation Guide Part no /663 On the CD-ROM and at Set up a populated chassis ready for use PXI Modules Installation Guide for Chassis Part no /667 On the CD-ROM and at Set up and use the universal PXI application for system configuration and operation PXI Studio 2 User Guide Part no: 46892/809 At 4

5 PREFACE Preface Hybrid slot compatibility PXI chassis that provide hybrid slots can accept both PXI Express modules and hybrid-compatible PXI modules. Hybrid-compatible PXI modules have a missing section of connector (see Fig. 1), which allows them to be inserted into both hybrid slots and standard PXI-1 slots. Because of the reduced connectivity of Cobham hybrid-compatible PXI modules, the PXI parallel local bus LBL[0] [12] disappears, to be replaced by the serial connection LBL[6], which is typically used to provide list addresses to a 3010 Series RF Synthesizer. Fig. 1 Standard PXI 1-slot connector (L) and hybrid-compatible PXI connector (R) The Cobham 3066 PXI Multi-way Active RF Combiner module fits in both hybrid-compatible and standard slots: 3066 Hybrid-compatible and standard PXI 1-slot Number of slots The 3066 occupies two slots in the chassis. 5

6 PREFACE Patent protection The 3066 PXI Multi-way Active RF Combiner is protected by the following patent application: UK Patent Application no

7 Introduction GENERAL INFORMATION This is the user manual for the Cobham 3066 PXI Multi-way Active RF Combiner module (referred to generically in this document as 3066 ). The combiner operates over the following frequency range: 3066 All ports: 250 MHz to 6.0 GHz and the following maximum power handling at the ports: RF INPUT DUT1 4 Applications dbm avg/cw +34 dbm avg/cw +38 dbm PEP This high-performance module simultaneously tests up to four full duplex mobile communication devices when used with a single vector signal generator and vector signal analyzer. It combines four-way splitter and combiner, configurable amplifiers, high isolation RF switches and duplexing combiners in a 3U high two-slot PXI module. This module is intended for use in RF test systems with the PXI 3000 Series RF modules. Together, these modules enable compact, high performance modular RF test systems to be developed that lower the cost of testing in highvolume manufacturing. Testing For receiver testing, the combiner allows the output from a single vector signal generator to be broadcast to or multiplexed between up to four full duplex DUT test interfaces. The output level at each test port can be adjusted independently and maintained stable with temperature, ensuring that exactly the right RF level is maintained at the DUT s input regardless of external losses. Receiver sensitivity measurements for multiple devices are performed concurrently, saving test time. 7

8 GENERAL INFORMATION For transmitter testing, the combiner provides RF power combining or multiplexing between up to four full duplex DUT test ports and a single vector signal analyzer. In calibrating a test system, path losses should be measured from the Vector Signal Analyser to each DUT (including all cables and fixtures between the 3066 and the DUT) this is to prevent large measurement uncertainties due to uncertainty stacking and mismatch error, and is essential to be able to properly compensate measurement results. The 3066 reports temperature-dependent loss data as a change in loss; this may then be used as an additional compensation factor. The 3066 does not report its absolute loss. List mode Path routing parameters can be controlled directly from software or from hardware list memory addresses. List mode enables very fast settling times for new routing configurations. Up to pre-defined lists of configurations can be stored and recalled. Each list entry contains the settings for each path between the DUT1 to 4 test ports and the RF input and RF output ports. List addresses can be routed to the 3066 in parallel or serial form. Parallel or serial list addresses may be input from the PXI trigger bus, or serial list addresses input via the front panel digital input/output (TRIG I/O A,B) connectors (configured via the routing matrix). The TRIG I/O A,B connectors may also be configured as outputs, for example to route a serial list address to another module. Source and receive paths have separate list memory areas, so the path routing for each is set up independently. For example, the source may be slaved to a signal generator list controller, and the receiver slaved to a digitizer list controller. Triggering and synchronization The 3066 provides flexible, configurable triggering from the TRIG I/O inputs on the front panel or from the PXI backplane. Triggers can be used for addressed selection or stepped incrementing of list mode. An update is triggered either by a change of list address (for example, a new serial list address is received or a manual list address is changed), or a change to the list data for the selected channel. Signal routing A configurable routing matrix allows you interconnect signals on the PXI backplane, the front-panel inputs, and the module s internal functions. Predefined routing scenarios can be loaded, or new scenarios created to meet particular requirements. 8

9 GENERAL INFORMATION Calibration System level calibration must be perfomed to compensate for the 3066 insertion loss. In operation, the source (downlink) path can establish equal power levels for each DUT by using a fine level control circuit. This also applies temperature compensation to ensure source accuracy over temperature. The receive (uplink) path reports level compensation data based on the difference between reference temperature and actual temperature. This data can be used to offset the measured level to maintain accuracy. Software The 3066 combiner is supplied with a VXI PNP driver, a C interface DLL, and a.net assembly. PXI Studio 2, supplied with the module, configures your PXI modules as logical instruments using an intuitive and powerful graphical interface. PXI Studio 2 provides comprehensive signal generator, digitizer and spectrum analyzer applications and optional analysis plugins to suit specific communications systems. Deliverable items 3066 Multi-way Active RF Combiner PXI module PXI Modules CD-ROM (part no /028), containing drivers, application software, data sheets, installation guides, safety instructions and user manuals for this and other modules in the 3000 Series Test results data CD-ROM, also contains calibration certificate: part no /054 Cobham PXI Modules Safety Instructions: printed item, part no /882 SMA connector cable: part no /738; 1 off SMA connector cable: part no /739; 1 off 9

10 GENERAL INFORMATION Specifications For the latest specifications, see the data sheet included on the CD-ROM (part no /028) or go to the Cobham website at All specifications are defined when used in conjunction with the driver software supplied with the module, or a later version. Warm-up time Allow at least 30 minutes for a module to warm up and meet its specifications fully after booting. 10

11 INSTALLATION Initial visual inspection Refer to the PXI Modules Common Installation Guide (part no /663) on the PXI Modules CD-ROM (part no /028). Hardware installation Before installing the module into the chassis, check that: (a) (b) no foreign conductive bodies are present between pins on the backplane or module connectors no pins on the backplane or module connectors are bent or damaged. Installing the module into the PXI chassis Refer to the PXI Modules Common Installation Guide (part no /663) and PXI Modules Installation Guide for Chassis (part no /697) on the PXI Modules CD-ROM, part no /028. These guides provide information such as specific precautions to take, positioning and fitting the module, installing hardware drivers, and so on. Install slot blockers (part no /587) in positions in the chassis where no module is fitted. It is essential to use slot blockers with air baffles to optimize the airflow around the This will reduce the temperature of the 3066 module when high RF powers are applied to the DUT ports for extended periods. Handling precautions Refer to the PXI Modules Common Installation Guide (part no /66) on the PXI Modules CD-ROM (part no /028). 11

12 INSTALLATION Connector care and maintenance Refer to the PXI Modules Common Installation Guide part no /663 for information on how to connect and torque SMA connectors, and how to protect and maintain all connectors. 12

13 Front-panel connectors OPERATION 1 TRIG I/O A,B TTL inputs/outputs, typically used for routing serial list addresses from other modules. SMB sockets, high impedance. 2 RF IN RF input from signal generator. SMA socket, 50 Ω. 3 RF OUT RF output to signal analyzer. SMA socket, 50 Ω. 4 DUT1 4 Duplexing combiner inputs/outputs for connection to device under test. SMA sockets, 50 Ω. Maximum safe powers DUT1 4: +34 dbm avg/cw, +38 dbm PEP, 0 V DC RF IN: +25 dbm avg/cw, 16 V DC RF OUT: +17 dbm avg/cw, 16 V DC TRIG I/O A,B: TTL, 5 V DC Fig front panel 13

14 OPERATION Software You can write your own code to run the 3066 module, using the function libraries supplied with the installer. See Programming below. Or you can run the module from PXI Studio 2, which lets you quickly set the module up to digitize and perform spectrum analysis on a variety of modulation schemes, using a graphical interface. Programming Use the afmac DLL C dll and Plug&Play CVI APIs. Object-oriented programming is provided by the.net assembly (afmacdotnet.dll). Detailed help information This user manual provides an overview of the facilities that the module provides and summarizes its operation; however, refer to the help files for detailed descriptions of functions, together with their parameter lists and return values. 14

15 OPERATION PXI Studio 2 Configuration To use PXI Studio 2 (supplied on the CD-ROM) with the 3066 and any other modules in the chassis, PXI Studio 2 must be configured to recognize the new modules. Do this by starting PXI Studio 2 and selecting Config\System Configuration. This shows the standard Hardware Configuration screen. Full details of how to configure the modules can be found in the PXI Studio 2 User Guide, part no /

16 OPERATION Applications Measuring multiple transceivers for receiver sensitivity Four UEs (user equipments) synchronize to a common broadcast downlink through the The UEs remain synchronized as the combiner switches their transmit outputs sequentially to the vector signal analyzer, greatly reducing test time normally lost in setting up individual UEs. Vector Signal Generator Rx #1 to # Tx/Rx #1 Tx/Rx #2 Vector Signal Analyzer Tx #4 Tx #3 Tx #2 PXI Multi-way RF Active Combiner Tx/Rx #3 Tx/Rx #4 Multiple RF I/O Connect the 3066 to a device with multiple RF I/O ports, such as a smart phone, and use a single vector signal generator and vector signal analyzer. Make measurements without complex switching arrangements, and reduce measurement uncertainty. Routing matrix Use the routing matrix to interconnect signals between ports and backplane. Routing matrix signals are shown in the following tables. All signals are active high. Bit 6 of ROUTE MATRIX inverts the selected input when set. 16

17 OPERATION Input codes 0 PXI TRIG SRC_LA(0) 48 RCVR_LA(0) 1 PXI TRIG SRC_LA(1) 49 RCVR _LA(1) 2 PXI TRIG SRC_LA(2) 50 RCVR _LA(2) 3 PXI TRIG 3 19 GND 35 SRC_LA(3) 51 RCVR _LA(3) 4 PXI TRIG 4 20 D_IO_2_IN 36 SRC_LA(4) 52 RCVR _LA(4) 5 PXI TRIG SRC_LA(5) 53 RCVR _LA(5) 6 PXI TRIG SRC_LA(6) 54 RCVR _LA(6) 7 PXI TRIG SRC_LA(7) 55 RCVR _LA(7) 8 PXI STAR SRC_LA(8) 56 RCVR _LA(8) 9 PXI LBL SRC_LA(9) 57 RCVR _LA(9) SRC_LA(10) 58 RCVR _LA(10) 11 OR OUT SRC_LA(11) 59 RCVR _LA(11) 12 AND OUT SRC_LA(12) 60 RCVR _LA(12) 13 SRC_LA_TX 29 DEBUG_IN 45 SRC_LA(13) 61 RCVR _LA(13) 14 RCVR_LA_TX SRC_LA(14) 62 RCVR _LA(14) 15 D_IO_1_IN SRC_LA(15) 63 RCVR _LA(15) 17

18 OPERATION Output codes 0 PXI TRIG 0 16 AND IN 3 32 SRC_HW_ADDR(0) 48 RCVR _HW_ADDR(0) 1 PXI TRIG SRC_HW_ADDR(1) 49 RCVR _HW_ADDR(1) 2 PXI TRIG SRC_HW_ADDR(2) 50 RCVR _HW_ADDR(2) 3 PXI TRIG 3 19 D_IO_1_OUT 35 SRC_HW_ADDR(3) 51 RCVR _HW_ADDR(3) 4 PXI TRIG SRC_HW_ADDR(4) 52 RCVR _HW_ADDR(4) 5 PXI TRIG 5 21 SRC_HW_UPD 37 SRC_HW_ADDR(5) 53 RCVR _HW_ADDR(5) 6 PXI TRIG 6 22 RCVR_HW_UPD 38 SRC_HW_ADDR(6) 54 RCVR _HW_ADDR(6) 7 PXI TRIG 7 23 SRC LA RX 39 SRC_HW_ADDR(7) 55 RCVR _HW_ADDR(7) 8 PXI LBL 6 24 RCVR LA RX 40 SRC_HW_ADDR(8) 56 RCVR _HW_ADDR(8) 9 OR IN 0 25 D_IO_2_OUT 41 SRC_HW_ADDR(9) 57 RCVR _HW_ADDR(9) 10 OR IN SRC_HW_ADDR(10) 58 RCVR _HW_ADDR(10) 11 OR IN 2 27 DEBUG_OUT 43 SRC_HW_ADDR(11) 59 RCVR _HW_ADDR(11) 12 OR IN SRC_HW_ADDR(12) 60 RCVR _HW_ADDR(12) 13 AND IN SRC_HW_ADDR(13) 61 RCVR _HW_ADDR(13) 14 AND IN SRC_HW_ADDR(14) 62 RCVR _HW_ADDR(14) 15 AND IN SRC_HW_ADDR(15) 63 RCVR _HW_ADDR(15) Note: D_IO_1 refers to front-panel socket TRIG IO A D_IO_2 refers to front-panel socket TRIG IO B. 18

19 OPERATION Program files Program files are installed onto your computer from the CD-ROM. Find.net assemblies, libraries, source and associated help files in the program installation folder on your computer. This is typically: C:\Program Files\Aeroflex\PXI All executable C DLLs are installed in typically one of either: C:\VXIPNP\WinNT\afMac\ or C:\Program Files\IVI Foundation\VISA\WinNT\afMac\ Driver export functions On-line help and functional documentation for driver export functions are available on the CD-ROM supplied with your module. They are installed onto your computer at the same time as the drivers. Driver installation folder Find help and functional documentation in the driver installation folder on your computer. If you did not change the default location, this is typically the same as for the VISA software. Help Within the driver installation folder is a help file that provides descriptions, lists of parameters, and return values: Their location is: afmacvxi.chm 3066 Visual BASIC help afmacvxi_c.chm 3066 C help These are PXI-compliant help files. and afmac.chm 3066 high-level C library help This is a non-pxi-compliant help file. 19

20 OPERATION The file opens at the Contents page: Hyperlinks from here take you to the Functions listings. Fig. 3 Online help contents page 20

21 OPERATION Functions listings Functions are grouped by type. Click on the hyperlink for details of the function. Each function has a description of its purpose, and may have a list of parameters and return values. Fig. 4 Function description example 21

22 Overview USING THE 3066 The 3066 Multi-way Active RF Combiner is a highly flexible signal routing and conditioning module. Its core elements are simple RF building blocks that combine to provide a sophisticated system for testing multiple devices or a multiple port device. This section covers the following key elements to assist in deploying the 3066 in your system: 3066 architecture; basic control of the 3066; calibrating a 3066-based test system for path loss compensation. 22

23 USING THE architecture Single device under test (DUT) Fig. 5 Testing a single device 23

24 USING THE 3066 In terms of testing a single DUT, the 3066 is essentially a power combiner. But in addition to the normal combining/splitting action it provides the ability to: independently isolate the source (signal generator) and the receiver (vector analyzer) from the DUT; provide three gain states for the source path, with a variable attenuator to provide fine level control; provide three gain states for the receive path. Multiple DUTs In fact, the 3066 provides four DUT ports, by using four-way power combiners at the RF IN and RF OUT ports (Fig. 6). Each DUT can be independently connected or isolated from the vector signal generator or vector signal analyzer. Each path s gain state may be set independently. Maximum flexibility of test setup is provided, however there are many RF paths to manage, and a large number of combinations of gain states. 24

25 USING THE 3066 Fig. 6 Testing multiple devices 25

26 USING THE 3066 Basic control of 3066 A detailed command reference for controlling the 3066 is provided in the help file which provides descriptions of functions, together with their parameter lists and return values. The following sections provide an overview of basic 3066 control to enable you to set a particular gain and routing configuration Source path settings The source path is from the RF IN connector to any one of the four DUT connectors. The signal direction is from RF IN to DUT. For each RF IN to DUT path the following parameters need to be set: the channel being used; the frequency of the signal being routed; the gain mode of the path; defining the path as being connected or isolated; gain offset. A small example is provided to illustrate the parameters. Channel The 3066 has source channels (numbered 0 to 65535). Each channel defines a combination of gain mode, frequency, isolation state and other source path parameters for all four source paths. Once the settings have been defined for a number of channels, the 3066 may then be rapidly changed to different state combinations by simply setting it to a previously defined channel. For each source path parameter that is set, the channel number is one of the passed parameters. The source path channel is independent of the receive path channel (so recalling a source path configuration does not alter the receive path). 26

27 USING THE 3066 Frequency For each source path, the loss is adjusted to minimize the difference between the four paths. To enable this to operate correctly, the 3066 needs to know the frequency of operation. Gain mode Each path may be set to one of three gains: 0, 1 or 2 (2 is the highest gain). The four paths may be set independently of each other. Isolation The isolation parameter defines if the particular path is Connected or Isolated. Gain offset You are able to set a variable attenuator in the gain path. This is to compensate for differences in external path losses between DUTs. Source path example RF INPUT DUT1 Gain 1, 2 GHz 3066 DUT2 DUT3 Gain 1, 2 GHz, 1dB Offset Gain 0, 2 GHz DUT4 NO CONNECTION Fig. 7 Source path example We wish to set up a 3066 as follows: We need a channel configured for rapid setting of the parameters. For this example we will use channel 5. Connections DUT 1 and DUT 2 are both configured to operate at 2 GHz with gain range 1. 27

28 USING THE 3066 The loss for the external cable to DUT 1 is 10 db. The loss for the external cable to DUT 2 is 9 db. We need an extra 1 db of attenuation to DUT 2 to ensure that the signal levels are balanced. The DUT 3 connection is set to gain range 0. This connection is used here to illustrate that gains may be set independently. The DUT 4 connection is not used and so is not connected (isolated.) DUT 1: First set the frequency Channel 5 DUT 1 afmacdll_source_channels_path_frequency_set( afmachandle, 5, 0, 2e9); 2 GHz Fig. 8 Source path example: set frequency afmachandle : when you use the 3066 API, you can control more than one To distinguish between instruments, each is assigned an instance handle. When you call the API, use the handle to identify which 3066 you are setting. The DUT ports are zero-indexed, so DUT 1 is 0, DUT 2 is 1 and so on. Set the gain mode afmacdll_source_channels_path_gainrange_set( afmachandle, 5, 0, 1); This function has a similar parameter list, but instead of frequency it is passed the needed gain range (in this case, 1). 28

29 USING THE 3066 Set the gain offset afmacdll_source_channels_path_gainoffset_set(afmachandle, 5, 0, 0.0); In this case the gain offset is 0 db. The default value is zero, so the gain offset would not usually need to be set to zero, unless you are overwriting a previously set value. Set the isolation state Make sure that the source path is not isolated (connect it, so a signal can go from RF IN to DUT 1) afmacdll_source_channels_path_isolation_set( afmachandle, 5, 0, AF_FALSE); If the last parameter is AF_TRUE, this source path is isolated (not connected). Now do the same for the other paths: DUT2: Frequency afmacdll_source_channels_path_frequency_set( afmachandle, 5, 1, 2e9); Gain mode afmacdll_source_channels_path_gainrange_set( afmachandle, 5, 1, 1); Gain Offset afmacdll_source_channels_path_gainoffset_set(afmachandle, 5, 1, -1.0); (value passed is -1 db, so the path for DUT 2 has been set to have 1 db more loss) Isolation State afmacdll_source_channels_path_isolation_set( afmachandle, 5, 1, AF_FALSE); DUT3: Frequency afmacdll_source_channels_path_frequency_set( afmachandle, 5, 2, 2e9); Gain Mode afmacdll_source_channels_path_gainrange_set( afmachandle, 5, 2, 0); This time we are setting the lowest gain range (0). 29

30 USING THE 3066 Gain Offset afmacdll_source_channels_path_gainoffset_set(afmachandle, 5, 2, 0.0); As previously stated, the default is zero, so we do not really need to send this. Isolation State afmacdll_source_channels_path_isolation_set( afmachandle, 5, 2, AF_FALSE); DUT 4: afmacdll_source_channels_path_isolation_set( afmachandle, 5, 3, AF_TRUE); DUT 4 is not used, so there is no need to set the other parameters. We can just set it to be isolated. 30

31 USING THE 3066 Receive path settings The receive path is from any one of the four DUT connectors to the RF OUT connector. The signal direction is from DUT to RF OUT. For each DUT to RF OUT path, the following parameters need to be set: the channel being used; the frequency of the signal being routed; the gain mode of the path; defining the path as being connected or isolated. The primary difference compared to the source path is that there is no Gain Offset parameter. Channel The 3066 features channels (numbered 0 to 65535). Each channel defines a combination of gain mode, frequency, isolation state and other receive path parameters for all four receive paths. Once the settings have been defined for a number of channels, the 3066 may then be changed rapidly to different state combinations by simply setting it to a previously defined channel. For each receive path parameter that is set, the channel number is one of the passed parameters. The receive path channel is independent of the source path channel (so recalling a receive path configuration does not alter the source path). Frequency For each receive path, the 3066 has calibration data for the change of gain over temperature. This data is frequency-dependent; hence the frequency of operation is required to enable the correct loss variation data to be recalled. Gain mode Each path may be set to one of three gains: 0, 1 or 2 (2 is the highest gain). The four paths may be set independently of each other. 31

32 USING THE 3066 Isolation The isolation parameter defines if the particular path is Connected or Isolated. Receive path example DUT1 NO CONNECTION 3066 DUT2 DUT3 NO CONNECTION Bypass gain, 900 MHz RF OUTPUT DUT4 High gain, 2.1 GHz Fig. 9 Receive path example We wish to set up a 3066 as follows: We need a channel configured for rapid setting of the parameters. For this example we use channel 7. Connections DUT 1 and DUT 2 are not used and so are not connected. DUT 3 is used for a GSM900 mobile operating at full transmit power, +33 dbm. Gain range 0 is used. DUT 4 is used for a WCMDA connection that is operating at a transmit power of -50 dbm. Gain range 2 is used. Note: This is an example configuration to demonstrate measurement of two different frequency bands using the Typically, the two bands would be connected to sequentially. 32

33 USING THE 3066 DUT 1: afmacdll_receive_channels_path_isolation_set( afmachandle, 7, 0, AF_TRUE); DUT 1 is not used, so there is no need to set the other parameters. We can just set it to be isolated. The function parameter list is very similar to the list for setting the source path: instrument handle; channel; DUT port; function dependent value. DUT 2: afmacdll_receive_channels_path_isolation_set( afmachandle, 7, 1, AF_TRUE); DUT 2 is not used, so there is no need to set the other parameters. We can just set it to be isolated. DUT 3: Frequency afmacdll_receive_channels_path_frequency_set( afmachandle, 7, 2, 900e6); Gain mode afmacdll_receive_channels_path_gainrange_set( afmachandle, 7, 2, 0); Isolation state afmacdll_receive_channels_path_isolation_set( afmachandle, 7, 2, AF_FALSE); DUT 4: Frequency afmacdll_receive_channels_path_frequency_set( afmachandle, 7, 3, 2.1e9); Gain mode afmacdll_receive_channels_path_gainrange_set( afmachandle, 7, 3, 2); Isolation state afmacdll_receive_channels_path_isolation_set( afmachandle, 7, 3, AF_FALSE); 33

34 USING THE 3066 Recalling channel settings The source and receive path channels are independent. To recall a previously defined channel use either of the following commands: Source path afmacdll_source_channelindex_set( afmachandle, 5); This recalls source channel 5, which was used in the source channel example. Receive path afmacdll_receive_channelindex_set( afmachandle, 7); This recalls receive channel 7, which was used in the receive channel example. 34

35 USING THE 3066 Calibrating a 3066-based test system for path loss compensation Typical test setup RF INPUT DUT1 Device 1 Signal Generator 3066 DUT2 Device 2 DUT3 Device 3 RF OUTPUT DUT4 Device 4 Vector Analyser Short Inter-Connect Cable RF Cable, 1 per Device Attenuator Pad (Matching) Final Connection to Device (typically SMA-MMCX Cable or SMA-Probe within a test jig) Fig. 10 Multiple device setup This figure shows a typical multiple device test setup using the With the 3066 within a PXI chassis, use short interconnect cables between the 3066 and the signal generator and vector analyzer. 35

36 USING THE 3066 The RF cables used to connect from the 3066 to the devices under test are usually much longer than the PXI interconnect cables. A matching attenuator pad is usually placed at the end of the test cable to improve the return loss seen by the device under test by masking any mismatch introduced by the long cable. Finally, the connection to the device is usually via MMCX or other similar push-on connection, and a small interseries cable is used. Alternatively, the device may be connected to via a test probe within a jig/fixture. Source path For a particular test frequency, we need to know by how much to offset the signal generator set power (the power level instruction sent to the signal generator) so that the desired power level appears at the device being tested. KEY FACT 3066 path to path error RF level matching For each source path, set the required gain mode and frequency. If all four source paths are set to the same gain mode and frequency, then: the maximum variation in insertion loss at the frequency of interest between paths (measured from the RF Input port to DUT port) is typically <0.25 db; this is maintained over a user specified temperature window, typically ±5 C; variation between external RF cables can then be compensated for by use of the 4 db (0.1 db step) fine level control attenuator featured in each path. This is called GainOffset in the 3066 API. 36

37 USING THE 3066 Signal generator offset Offset due to losses and mismatches. RF INPUT DUTn Device n 3066 SET Power Actual Incident Power Fig. 11 Signal generator power offset The loss of the RF path from the signal generator to the device test interface needs to be measured, and this loss is then used to offset the signal generator output power. There are errors in the level of the presented RF power, due to mismatch errors at either end of the RF path and the level accuracy of the signal generator. The excellent input match of the 3066 minimizes mismatch errors with the signal generator. The matching attenuator adjacent to the device under test minimizes any mismatch error due to the return loss of the device under test. 37

38 USING THE 3066 Assessing the source path loss Power Sensor RF INPUT DUTn Power Sensor 3066 SET Power Fig. 12 Source path calibration configuration To assess the source path loss, two power sensors and a calibrated two-resistor type power splitter are used. The first power sensor and calibrated splitter enable a known input power to be presented to the The second power sensor at the device test interface may then be used to measure the incident power and so calculate the loss through the 3066 source path. 38

39 USING THE 3066 Alternative setup 1 RF INPUT DUTn Power Sensor 3066 SET Power 2 RF INPUT DUTn Device n 3066 SET Power Fig. 13 Alternative source path calibration configuration Alternatively we may omit the first power sensor and calibrated splitter. This means that the level error of the signal generator is now included in the calculated loss. The level error may be different for different set power levels. 39

40 USING THE 3066 The power sensor has a measurement uncertainty and there is a mismatch error between the sensor and the point where it is connected in the path. However, the 3066 features excellent output match on all its DUT ports, and by using good quality RF cables this uncertainty error is minimized. Consult your power sensor manufacturer s manual for guidance on assessing the measurement uncertainty of the recorded power sensor measurement. Calculate the offset The offset to apply to the signal generator s set power level is the measured loss. This offset may then be modified by a small factor to compensate for the loss of any unmeasured cable (e.g. the SMA-MMCX inter-series cable). This is usually of the order of <0.5 db. 40

41 USING THE 3066 Source path fine level control The four source paths of the 3066 each have an independent fine level control to equalize the power level incident to each device being tested. For a given frequency, the four paths may have different offset values. Clearly, the signal generator cannot be set to four different power levels simultaneously. Instead, the fine-level control attenuator (called GainOffset in the API) may be used to modify each of the four channels to equalise the power incident to the device. This sets a temperature-calibrated variable attenuator. The 3066 contains extensive temperature calibration data, and provides API functionality to maintain a constant path loss (from the RF INPUT to DUT port) over a temperature window of typically ±5 C. You may set the temperature window. The smaller the temperature window used, the better the 3066 maintains a constant path loss. You should only use as large a temperature window as you need. The basic procedure for using the fine level control is: Pre-calibration Set the required temperature window; set the required frequency of operation; read the current 3066 temperature; set the current reference temperature (equal to above); set the 3066 Source Path Gain mode; set gain offsets to zero and apply at current temperature. 41

42 USING THE 3066 Calibration Measure the path loss from the signal generator to the device for each path; calculate the required gain offsets. Application Set the signal generator to achieve a desired output power; set the desired amount of gain offset; apply the desired gain offset. The 3066 applies temperature compensation within the temperature window. Key points: Path loss is measured at the reference temperature; each time you use the source path, you can send a refresh channel command. This measures the current 3066 temperature, and use calibration data to adjust the loss so that the current loss is the same as that at the reference temperature. 42

43 USING THE 3066 Fine level control example RF INPUT DUT1 Device 1 Signal Generator 3066 DUT2 Device 2 DUT3 Device 3 RF OUTPUT DUT4 Device 4 Fig. 14 Example setup for fine level control For this example we assume that there are going to be four devices. As shown in the figure, the connection to the 3066 is as follows: 3066 RF cable attenuator SMA/MMCX adaptor device We wish to achieve a power level of -10 dbm at each device at 2 GHz. Cable and attenuators The attenuator has a nominal loss of 6 db. The SMA/MMCX adaptor cables have an assumed loss of 0.2 db each. The RF cable and attenuator combinations will have slightly different losses for each device. Pre-calibration The 3066 current temperature is read from the The 3066 reference temperature is set (using the read back temperature as the value). 43

44 USING THE 3066 Calibration All four 3066 source paths are set to the following: high gain mode; gain offset = 0 db; frequency = 2 GHz; output state = Isolated. The signal generator is set to -20 dbm, frequency 2 GHz, CW. For each DUT port in turn the following is performed: power sensor connected to last SMA connection (typically the matching attenuator, unless the power sensor has a MMCX connection); output state = Connected; the received power is measured and recorded; output state = Isolated. For this example, we assume the following results were obtained: DUT Measured power Gain (based on 20 dbm input)

45 USING THE 3066 The required gain offsets to apply to the 3066 paths are as follows: DUT Gain offset Comment ( 27.5) ( 27.2) ( 27.5) ( 27) ( 27.5) ( 27.4) 4-0 Lowest gain The offset to apply to the signal generator output level is: OFFSET = SET_POWER MEASURED POWER CABLE_FACTOR (cable factor = gain of the cable (which is a loss)) = 20 ( 27.5) ( 0.2) (use the lowest measured power) = To achieve 10 dbm at each device: SET_POWER = DESIRED_POWER + OFFSET Signal generator = 10 + (+7.7) = 2.3. Each path has been equalised to a have a gain of 7.5. The final SMA/MMCX transition is assumed to have a loss of 0.2 db: final power = = 10. Now all four devices will have the same incident power level. The path loss of the 3066 is maintained with temperature using the refresh channel command. 45

46 USING THE 3066 Receive path For a particular test frequency, we wish to know how much to offset the received measured power to derive the actual DUT output power. The receive paths of the 3066 are designed to have similar gains in the same gain mode but they do not feature variable attenuation (unlike the source path). This means that a different gain is presented by each receive path. Receive path offset Offset due to losses and mis-matches. RF OUTPUT DUTn Device n 3066 MEASURED Power Actual Incident Power Fig. 15 Digitizer measured power offset As described for the source path, the loss of the path from the device test interface to the digitizer is measured, and the loss used to offset the digitizer measured power. There are errors in the level of the reported RF power, due to mismatch errors at either end of the RF path and the level accuracy of the digitizer. 46

47 USING THE 3066 Assessing the path loss Power Sensor RF OUTPUT DUTn 3066 Power Sensor MEASURED Power Fig. 16 Assessing receive path loss To assess the loss of the receive path, a signal generator, power sensor and calibrated two-resistor type power splitter are used. In this way a known signal level is presented at the device test interface. The power at the digitizer is then measured. This may be measured using a power sensor. The loss through the path may then be calculated. Alternatively, the power may be measured directly using the digitizer, in which case the loss includes the level error due to the digitizer and its mismatch uncertainty. However, if the loss is evaluated using the digitizer, the included level accuracy is only for the current input attenuation settings of the digitizer. As with the source calibration, you may wish to measure the loss over a number of digitizer input settings, which will account for level accuracy variation due to input attenuation. Calculate the offset The offset to apply to the receive path is the measured loss. 47

48 USING THE 3066 This offset may then be modified by a small factor to compensate for the loss of any unmeasured cable (e.g. the SMA-MMCX inter-series cable). This is usually of the order of <0.5 db. 48

49 USING THE 3066 Receive path loss compensation with temperature The receive path does not feature fine level control. Each of the four receive paths has a slightly different loss from the others for the same frequency and gain mode. This means that a record of all four path losses must be stored and applied to measurements. The 3066 features a mechanism for reporting the change in receive path loss over temperature. The enables you to modify their correction factors over time to maintain system calibration. The basic procedure for using loss temperature compensation is: Pre-calibration Set the required frequency of operation; set the 3066 s receive path gain mode. Calibration Read the current 3066 receive path temperature: store this as the reference temperature; measure the path loss from the device to the signal analyzer for each path. Application Set the signal analyzer to measure a desired reference level; obtain the latest change in path loss to provide best measurement correction; measure signal and apply correction (path loss and latest path loss change). 49

50 USING THE 3066 Loss compensation example RF INPUT DUT1 Device 1 Vector Analyser 3066 DUT2 DUT3 Device 2 Device 3 RF OUTPUT DUT4 Device 4 Fig. 17 Example set-up for receive path loss compensation For this example we assume that there are going to be four devices. As shown in the figure, the connection to the 3066 is as follows: 3066 RF cable attenuator SMA/MMCX adaptor device Cable and attenuators The attenuator has a nominal loss of 6 db. The SMA/MMCX adaptor cables have an assumed loss of 0.2 db each. The RF cable and attenuator combinations have slightly different losses for each device. 50

51 USING THE 3066 Calibration All four 3066 receive paths are set to the following: gain range = 0; frequency = 2 GHz; input state = Isolated. An external signal generator is set to 0 dbm, frequency 2 GHz, CW. A power sensor is connected to the signal generator output to ensure 0 dbm is applied to the receive path input. The current temperature of the 3066 receive path is interrogated and stored as Reference Temperature. For each DUT port in turn, the following is performed. signal generator connected to last SMA connection (typically the matching attenuator, unless the signal generator has a MMCX connection); input state = Connected; the received power is measured and recorded by the VSA; input state = Isolated. For this example, assume the following results were obtained: DUT Measured power Gain (based on 0 dbm input) Performing measurements We wish to measure the output power of device 2 at 2 GHz. 51

52 USING THE 3066 The device has an output power of 1.3 dbm The 3066 is interrogated for its change in loss due to temperature for the receive path for device 2: 3066_RECEIVE_CHANGE = db (say) 3066 is set to measure device 2. Reported power from the VSA is dbm. To correct this figure to obtain the actual device output power: OFFSET = GAIN CABLE_FACTOR _RECEIVE_CHANGE = = The power level that is then recorded is: ACTUAL = MEASURED_POWER OFFSET = ( 37.45) = 1.3. The correction for the known loss for each receive path is applied as needed loss variation with temperature for each receive path may be interrogated and used to augment this correction. In this way all four devices may be measured. 52

53 APPLICATION-BASED MEASUREMENTS Setting up the 3066 for typical application measurements There are many measurements that are performed for the commonly used mobile and cellular technologies, along with a large number of mobile standards. It is therefore a considerable requirement to ask of the measurement professional to have knowledge of all the technologies, and to combine this with an understanding of the RF settings required for test equipment. To make this task easier, this section examines the needed Source and Receive path settings for each of the major technologies utilizing the 3066 Multi-way Active RF Combiner. 53

54 APPLICATION-BASED MEASUREMENTS Typical test system A typical PXI3000 test system comprises a signal generator, signal analyzer and combiner. A configuration typically uses a 3025C Signal Generator, 3035C Digitizer and 3066 Multi-way Active RF Combiner: Fig. 18 Typical practical test system setup 54

55 APPLICATION-BASED MEASUREMENTS The 3066 makes multi-dut test systems possible by providing complex signal switching in a convenient PXI formfactor module so that only connections from the 3066 DUT test port to the DUT are required (see 3066 architecture for examples of single- and multiple-device connections for testing). Choosing the receive gain range In measuring the absolute output power of a DUT, with a loss between the digitizer and DUT output, the previously measured system loss figure is used to offset the measurement results to obtain the actual DUT output power. The expected DUT power is known and so the reference level of the digitizer may be set to the optimum measurement range. This is usually found by RequiredDigRefLevel = Expected DUT RMS Power + RequiredHeadroom KnownLoss The RequiredHeadroom is the crest factor / peak-average power ratio of the RF signal, the value of which varies by technology standard. Where the required digitizer reference level RequireDigRefLev is greater than the maximum reference level available, you should review the external cabling and attenuation and increase this to ensure that the digitizer does not experience power levels that may cause damage to the instrument. When using the 3066, the above formula for assessing the digitizer reference level still applies. However, there is an additional step to make: selecting the correct gain range appropriate for the expected power level. Use the following procedure to select the most appropriate gain range based on your DUT s expected output power level and technology. The aim is to select the highest gain range to maximise measurement sensitivity, whilst not exceeding input power limits of the 3066 to ensure the measured signal is not compromised. The pseudo variables in the following description are for example purposes only and do not indicate actual variable names used in the 3066 API. 55

56 APPLICATION-BASED MEASUREMENTS The pseudo variables are: ReceiveLoss_GainRangeX (0,1 and 2) EstDUT_3066Loss 3066NominalGain DUTPeakPower DUTRmsPower PAPR Est3066_InputPowerRMS Est3066_InputPowerPeak Expected3066OutputGainRangeX (0, 1 and 2) Nom3066MaxOutputPowerX (0, 1 and 2) Expected3066OutputPowerX (0, 1 and 2) MaximumDigitizerInputPower System losses from the DUT test interface to the digitizer input port should already have been established for each 3066 receive path gain range setting for the operating frequency. ReceiveLoss_GainRange0, ReceiveLoss_GainRange1, ReceiveLoss_GainRange2 Estimated path losses from the DUT test interface to the 3066 input port should be established, either by: or knowledge of the external cabling and attenuation between the DUT test interface and the 3066 subtracting the 3066 nominal receive gain for each gain range setting from the known system loss. Normally the path from the 3066 s output to the digitizer is a short cable of typically, <0.5 db loss; if this loss is known to be more significant it should be accounted for nominal gain may be found using the afmacdll_receive_nominalloss_get API call (the value returned is a gain, and is frequency dependent.) 56

57 APPLICATION-BASED MEASUREMENTS EstDUT_3066Loss = ReceiveLoss_GainRangeX 3066NominalGain (double to change the gain into a loss) Establish the expected peak output power from the DUT: This is the Expected RMS power + the Peak-Average Power Ratio for the technology to be measured. DUTPeakPower = DUTRmsPower + PAPR Does the DUT output power exceed the rated power of the 3066 input port? Establish the input power level to the 3066 if the power is too high then additional external attenuation should be fitted. Est3066_InputPowerRMS = DUTRmsPower EstDUT_3066Loss Est3066_InputPowerPeak = DUTPeakPower EstDUT_3066Loss The maximum incident powers (RMS and peak) are identified in the 3066 datasheet. Would the output power from the 3066 for a particular gain range exceed the nominal maximum output power? If so then that gain range should NOT be used. Establish the nominal maximum output power (Nom3066MaxOutputPowerX) using the afmacdll_receive_rangeparameter_get API call with afmacdll_maxnominalportoutputpower enumeration. Expected3066OutputPowerX = DUTPeakPower ReceiveLoss_GainRangeX If (Expected3066OutputPowerX > Nom3066MaxOutputPowerX) then Do Not use Gain Range X 57

58 APPLICATION-BASED MEASUREMENTS Would the output power from the 3066 for a particular gain range exceed the maximum input power level of the digitizer? If so, then that gain range should NOT be used. Use the expected output powers calculated previously. The maximum digitizer input power may be established from the digitizer datasheet. If (Expected3066OutputPowerX > MaximumDigitizerInputPower) then Do not use Gain Range X It is not expected that the output power from the 3066 will exceed the digitizer maximum input level, but this is a simple check to make and should be performed to ensure that do not damage your equipment. Now select the 3066 gain range to use. Ideally, choose the highest gain range whose expected output power does not exceed its nominal maximum output power. 58

59 APPLICATION-BASED MEASUREMENTS Maximum uplink power levels, crest factors/peak-average power ratio and external losses Technology Uplink PAPR db Calibrated DUT uplink RMS power max dbm External attenuation db to prevent damage to 3066 (including path losses from 3066 to DUT) 1,2 WCDMA GSM EDGE CDMA TD-SCDMA LTE WLAN (a,b,g,n) WiMAX Notes DUT port max power handling +34 dbm CW, +38 dbm PEAK attenuation selected based on worst case of either CW or peak to ensure neither of these values is exceeded. 2 Attenuations based on highest output power for a technology. When testing lower-power devices, it is recommended that attenuation should be reduced. 3 The power profile for GSM/EDGE includes + 4dB on the rising edge of the power profile. 59

60 APPLICATION-BASED MEASUREMENTS Choosing the source gain range When setting the output level of the signal generator to provide an input signal to the DUT, the previously measured system loss figure is used to offset the signal generator set power (the commanded power sent to the signal generator) to ensure that the correct power is presented to the DUT. The signal generator set power is usually found by: Signal Generator Set Power = Desired Input Power to DUT + Known Loss Where the required signal generator set power exceeds the maximum power available from the signal generator, you should review the external cabling and attenuation and decrease this. When using the 3066, the above formula for setting the signal generator set power still applies. However, there is an additional step: selecting the correct gain range appropriate for the target output power level. Use the following procedure to select the most appropriate gain range based on your target output power level and technology. The aim is to select the lowest gain range to prevent compromise of the output signal quality whilst ensuring that the target power level is achieved. The pseudo variables in the following description are for example purposes only and do not indicate actual variable names used in the 3066 API. The pseudo variables are: SourceLoss_GainRangeX (0,1 and 2) DUTInputPeakPower DUTInputRmsPower PAPR Nom3066MaxInputPowerX (0, 1 and 2) Expected3066InputPowerX (0, 1 and 2) System losses from the signal generator output port to the DUT test interface should already have been established for each 3066 source path gain range setting for the operating frequency. SourceLoss_GainRange0, SourceLoss_GainRange1, SourceLoss_GainRange2 Establish the expected peak output power to be input to the DUT 60

61 APPLICATION-BASED MEASUREMENTS This is the Expected RMS power + the Peak-Average Power Ratio for the technology to be measured. DUTInputPeakPower = DUTInputRmsPower + PAPR Alternatively, if using a PXI3000 signal generator, the.aiq file used to generate the waveform may be inspected for its crest factor value this provides the exact PAPR for the specific waveform to be generated. Would the input power to the 3066 for a particular gain range exceed the nominal maximum input power? If so, then that gain range should NOT be used. Establish the nominal maximum input power (Nom3066MaxInputPowerX) using the afmacdll_source_rangeparameter_get API call with afmacdll_maxnominalportinputpower enumeration. Expected3066InputPowerX = DUTInputPeakPower + SourceLoss_GainRangeX If (Expected3066InputPowerX > Nom3066MaxInputPowerX) then Do Not use Gain Range X Now select the 3066 gain range to use. Ideally, choose the lowest gain range whose expected input power does not exceed its nominal maximum input power. 61

62 APPLICATION-BASED MEASUREMENTS Downlink test maximum power levels and crest factors/peak-average power ratio Technology Downlink PAPR db Downlink RMS power max dbm WCDMA GSM 0 30 EDGE 3 30 CDMA TD-SCDMA LTE WLAN (a,b,g,n) WiMAX

63 BRIEF TECHNICAL DESCRIPTION The 3066 is a high performance RF active combiner that increases the capacity of a test system by testing multiple devices simultaneously. High DUT-to-DUT isolation is maintained to ensure minimal interaction between DUTs during test. The 3066 combiner consists of three PCBs: RF source and receiver boards (which constitute the RF block) and a PXI interface board. The boards communicate over a serial bus. The RF block performs the signal combination and switching between ports. Independently-controlled multiplexer switches isolate individual source or receive paths. Switchable gain stages in both source and receive paths provide isolation, compensate for losses, and provide higher output power when required by the DUT. The gain stages have preset gain combinations, selectable by the GainRange property. The source gain ranges include a bypass setting, whereby the amplifiers are disconnected and the signal passed unamplified (passive mode). In each source path, a fine-level control circuit is provided to compensate for losses and level offsets, ensuring consistent levels at all test ports. Accurate fine-level balancing of the RF IN signal across all DUT ports is achieved via the system level calibration, using the Gain Offset property available for each DUT path. In the receive path, temperature compensation data for all paths is stored in the module, and used to compensate measurement results. An EEPROM stores module-related calibration data. Any RF path may be switched out to select the maximum isolation (insertion loss) between an unused or unwanted DUT port and other ports. This is controlled by the Isolation property available for each path. Source and receive isolations are independently selectable. The unwanted port is terminated in 50 ohm internally. RF switch control and combiner path calibration information is communicated via the PXI backplane, which enables inter-module communication via the PCI bus and provides control and power signals to the module. Fig. 19 shows a block schematic for the

64 BRIEF TECHNICAL DESCRIPTION Fig simplified block diagram 64