Demonstration Board Documentation / (V1.0) Ultra linear General purpose up/down mixer Features: Very High Input IP3 of 24 dbm typical Very Low LO Power demand of 0 dbm typical; Wide input range Wide LO Frequency Range: <500 MHz to >3.0 GHz Single-Ended Ports RF- and IF-Port Impedance 50 ohms Operating Voltage Range: <3 to 6 V Very Low Current Consumption: 6 ma typical All Gold Metalization 1. DESCRIPTION The is a general purpose up/down-converter device designed for multiple applications such as PHS mobile phones and BTS, cellular and PCS mobile phones and BTS, ISM bands, GPS receivers, L-band satellite terminals, WLAN and pagers. Due to its excellent intermodulation characteristics and its low conversion gain, is particularly suited for PHS and GSM BTS up/down converters. The device combines an ultra-linear mixer with LO driver in a very small MW-6 package. The mixer section of combines low conversion losses and excellent inter-modulation characteristics with low requirements of LO - and DC-power. The internal level controlled LO-Buffer enables a good performance over a wide LO level range. This document describes the demonstration board for the general purpose up/down mixer. It includes schematics, assembly drawings, Bill of Materials (BOM), and board construction information. It also highlights board losses and other information that could affect For additional information and latest specifications, see our website: www.triquint.com 1
the performance of the with regard to comparisons with the Data Sheet specifications. An applications discussion is emphasized, and test data for the individual boards is included as a separate document. 2. DEMONSTRATION BOARD SCHEMATIC 3. DEMONSTRATION BOARD ASSEMBLY DRAWING Top Assembly Drawing 2 For additional information and latest specifications, see our website: www.tqs.com
4. DEMONSTRATION BOARD COPPER PROFILE The demonstration board for the is a four-layer board manufactured from FR-4 material. The dielectric constant of the material is approximately 4.6 at 1GHz. The thickness of the top dielectric layer is 125µm, resulting in a 50Ω line width of approximately 196µm. The remaining dielectric layers are not critical and their thickness is set to achieve the correct mechanical thickness of the board assembly. The top and bottom copper layers have a thickness of about 53 microns after plating and the interior copper layers have a thickness of about 36 microns. The actual board layers are shown below. For additional information and latest specifications, see our website: www.triquint.com 3
5. APPLICATIONS NOTE 6.1 Product description The is a general purposed ultra-linear up/down GaAs MESFET mixer with integrated LO-buffer for frequencies up to and exceeding 3GHz. A low LO-input power of typically -4dBm is sufficient to provide a very high input intercept point of typically 24dBm at 3V. The input and output ports are 50ohm matched. is suitable for CDMA base station/repeater, GSM/DCS base station/repeater, PHS base station/repeater, CDMA, WCDMA, DMB and WLAN application. 6.2 Implementation It is recommended that design engineers should follow the implementation procedure described below in order to optimize the performance and minimize the power consumption of the. The procedure has five simple steps. Before connecting power, all components should be soldered. Five important steps: 1. Tuning L4 for the minimum current consumption 2. LO-port input matching 3. Matching Network for the RF/IF 4. Fine tune for all components 4 For additional information and latest specifications, see our website: www.tqs.com
6.3 Application description 6.3.1 Tuning L4 for the minimum current consumption pin4 L4 C4 The uses negative voltage generator block to bias the integrated common source depletion mode GaAs MESFET LO buffer amplifier. A negative voltage generator block senses the output RF voltage at the LO buffer amplifier output and generates a gate bias DC voltage for the LO buffer FET. The DC power consumption can be optimized at the application frequency by varying the values of L4 and C4. L4 is the inductor connected between the output port of the internal LO-buffer (pin 4) and provides the DC power path to this portion of the. This application note recommends values of L4 and C4 but the designer can modify this value to fit his board. The first step in optimizing L4 and C4 is to measure the drain current. To monitor the real time current consumption variation with varying L4 values, the required LO-signal must be provided to the device. Therefore a reference matching network must be connected to the LOport before beginning the procedure. After the reference matching network has been connected, the design engineer should apply the local oscillation signal at the required LO-frequency and check the current consumption. The mixer RF input port (pin1) and the IF output port (pin 6) can be left open at this point. Similar to the LO-port matching network, the reference network and typical values for L4 and C4 are shown below. The design engineer should find the 4 values that the current consumption reaches minimum at the desired LO operating frequency and level. One suggested approach is by adjusting the LO-frequency to find the frequency at which the current consumption reaches the minimum point. If the minimum current occurs at a frequency lower than the desired LO frequency, a lower value inductor should be chosen for L4. If minimum current occurs at a higher frequency then a higher value inductor should be chosen. For additional information and latest specifications, see our website: www.triquint.com 5
LO Frequency L4 C4 700MHz 27nH 0.1uF 850MHz 18nH 0.1uF 1150MHz 10nH 0.1uF 1650MHz 3.9nH 0.1uF 1800MHz 3.3nH 22pF 2100MHz 2.2nH 12pF 2300MHz 1.2nH 8pF LO-power supply pin Reference values As shown dominant component determining current is L4 but C4 gives more optimization. Smaller C4 make LO target frequency move higher. If designer can not find optimized value with L4 and it is optimized a little bit lower frequency, good approach is decreasing C4 value. 6.3.2 LO Input port matching There is positive return loss near target LO frequency at LO buffer input using current optimized L4 and C4 because current optimized output circuit give more feedback from LO buffer output to input. This make LO buffer instable in the case of connecting bandpass filter. To prevent this at the LO input Triquint recommend stabilizing resistor (R1:330ohm) should be used. C1(0.1uF) is DC block capacitor to keep gate bias. Normally Designer need only L3 for below -10dB return loss at LO input port to 1GHz but C6 is needed for -10dB return loss above 1GHz. LO Frequency L4 C6 R1 C3 700MHz 22nH N.P 330Ω 1000pF 850MHz 18nH N.P 330Ω 1000pF 1150MHz 10nH N.P 330Ω 1000pF 1650MHz 6.8nH 2.2pF 330Ω 1000pF 1800MHz 5.8nH 1.5pF 330Ω 1000pF 2100MHz 4.7nH 1.2pF 330Ω 1000pF 2300MHz 3.9nH 1.5pF 330Ω 1000pF LO-port Reference Matching Network Designer can change R1 value but lower value give less gain at the LO buffer amplifier. 6 For additional information and latest specifications, see our website: www.tqs.com
6.3.3 Matching Network for the RF In/Output ports Actually pin 1 and pin 6 has common node in the die and bonded to different pins (pin1 and pin 6). Designer can use either pin for RF or IF (In this application note pin 1 is designated as RF and pin 6 is designated as IF for convenience). The final part of the implementation procedure is to provide the matching circuits for the Mixer input and output ports (pin1 and pin6). In principle, the RF input/output matching network should be an RF band-pass filter (to allow the RF band signal to pass into the Mixer and to reflect the IF signal). RF Filter (L1, C1) passes the RFfrequency and reflects the IF signal because series resonator is short-circuited at resonant frequency. An appropriate adjustment of the filters is the prerequisite to achieve a lower conversion loss. For the mixer RF input port matching circuit, we can determine the starting values by considering a simple L-C series resonant circuit where L = L1 & C = C1: 1 f = 2π LC For example, for a CDMA 800 application with a received RF signal of 881MHz, one possible combination of C1 and L1 values could be: C1 = 2pF (defined by customer) L1 = 16.3nH (calculated from eqn.6) Since the IF- and RF-filters are connected with the ohmic resistor of the switching FET (mixer FET), matching of either filter might influence the matching parameters of the other filter. For additional information and latest specifications, see our website: www.triquint.com 7
RF Frequency C1 L1 869-894MHz 1.8pF 18nH 1840-1870MHz 2.7pF 2.7nH 1930-1990MHz 2pF 3.3nH Mixer RF Input Matching Network Reference Values 6.3.3 Matching Network for the IF In/Output ports As mentioned above designer can use same design concept for IF matching. IF filter (L2, C2) suppresses the RF band and passes IF frequency because parallel resonator is open-circuited at resonant frequency. Triquint would recommend L2 and C2 for LO frequency suppress because LO power is a lot higher than RF power. L2 gives dominant IF signal path because usually IF frequency is lower than LO and RF (L2 value is relative small to pass IF frequency). Appropriate adjustment of the filters is the prerequisite to achieve a lower conversion loss. For the mixer IF in/output matching circuit, we can use same equation to determine the starting values by considering a simple L-C series resonant circuit where L = L2 & C = C2: 1 f = 2π LC C5 is DC-blocking capacitor which is 1000pF but designer can use C5 as additional matching component according to board layout. 8 For additional information and latest specifications, see our website: www.tqs.com
LO Frequency C2 L2 C5 869-894MHz 1.8pF 18nH 1000pF 1840-1870MHz 2.7pF 2.7nH 1000pF 1930-1990MHz 2pF 3.3nH 1000pF For additional information and latest specifications, see our website: www.triquint.com 9