Mansour Keramat. * No part may be reproduced without permission from the author. 1- Application of Data Converters. Contents

Transcription

1 Mansour Keramat Analog and Mixed Signal Laboratory Electrical & Computer Eng. Dept. University of Connecticut Storrs, CT URL: * No part may be reproduced without permission from the author. Contents I - Applications of Data Converters II - Design of Track and Hold III- Nyquist-Rate Converters IV- Oversampling Converters V- Digital-to-Analog Architectures VI - Test of Data Converters Page: 1-2

2 Page: 1-3 Outline 1- Why Data Converters 2- Wireless Communications 3-4- Voiceband Digital Communications 5- Smart Sensors 6- Data Storage 7- Digital Imaging 8- Video Systems 9- Test of Integrated Circuits 10- Motor Control 11- Digital Control Page: 1-4

3 Why Data Converters? Typical Application of Data Converters: Analog to Digital Converter Digital Network Digital to Analog Converter Analog Domain Page: 1-5 Wireless Communications Cellular Phones: Low Sampling Rate (8 ksps) 13 bits Antenna Voice Coding Channel Coding & Interleaving Encryption Modulation D/A RF Modulation PA D U PL D/A Voice Decoding Channel Decoding & Deinterleaving Decryption Demodulation & Equalization RF Demodulation RF/IF Conversion E X O R High Sampling Rate (20 MSPS) <8 bits Page: 1-6

4 Wireless Communications Ideal GSM Basestation: The intention is to bring the converter as near as possible to the RF antenna of the system. Antenna 890->915 MHz LNA LNA: Low Noise Amplifier : RF Filter Challenge: In GSM systems an analog input bandwidth of more than 900MHz would be required! Page: 1-7 Wireless Communications Realistic GSM Basestation: Antenna 890->915 MHz LNA 71 MHz ± 70 khz : RF Filter f LO IF Filter LNA: Low Noise Amplifier Pipelined or Converter Page: 1-8

5 Modems: Transmit and receive information through twisted pair wires. 1- High-speed voice band modems (56 kbps Modem) 2- Integrated Services Digital Network (ISDN) modems 3- Digital Subscriber Line (DSL) modems 4- Cable Modems 5- Wireless modems Page: 1-9 Digital Subscriber Line (DSL) Modems: Client Computer DSL Modem Fax Telephone Splitter For full Rate Local Loop 1K to 18K ft AWG, Copper Central Office Splitter DSL Line Card Voice Band Line Card ATM Frame Relay etc. Public Switched Telephone Network (PSTN) Page: 1-10

6 xdsl Modems: ADSL: Asymmetric DSL (1.5 Mbps) SDSL: Symmetric DSL (1 Mbps) RDSL: Rate-adaptive DSL (1.5 Mbps) IDSL: ISDN DSL (128 Kbps) CDSL: Consumer DSL (1 Mbps) HDSL: High-speed DSL (1.54 Mbps) VDSL: Very high-speed DSL (51 Mbps) Page: 1-11 Types of ADSL: 1- Carrierless Amplitude-Phase (CAP) 2- Discrete Moltitone (DMT) Both use Quadrature Amplitude Modulation (QAM) and 2-15 bits per tone. Amplitude Voiceband Telephony Upstream Data Downstream Data 4 khz 25 khz 138 khz 200 khz 1.1 MHz Page: 1-12

7 ADSL Analog Front-End (AFE): 2-bit serial port reset_n Clock 80MHz DCXO PLL Bias Control Tx: 1 bit 40Msps DAC PAA Line Driver Voltage swing: 7V pp-diff Line 1dB per step Hybrid Line replica ADC PGA Rx: 2 bit 80Msps fs=80mhz Eff bits=14 AFE Chip Page: 1-13 ADSL Chipset: Texas Instruments (TI) solution: Universal Digital Interface TNETD4100 ADSL Codec TNETD4020 Line Receiver THS6032 Rx ADSL Transceiver TNETD4200 Contains 14 bit and D/A Line Driver THS6062 Tx Transceiver performs the ADSL DMT modulation/demodulation, all initialization and training sequence of the ADSL specifications. Page: 1-14

8 ISDN Modems: 144 kbit Binary Sigma-Delta D/A 16 MHz 1-bit Clamp Circuit 3rd Order Smoothing Filter - TX Amp + 75 Ohm Subscriber Line 75 Ohm 150 R R 2R 2R Digital Code Digital Decimator Filter 16 MHz Second Order Sigma-Delta C Hybrid ISDN U-Interface (144 kbps) Page: 1-15 Gigabit Ethernet: It requires four 8-bit converters at the receiver end. The converters should operate at 125 Mega sample per second (MSPS). Although the resolution is not high, the power consumption is the main challenge in the design procedure. The dynamic range of the converters must be high enough to overcome the noise, interference, and attenuation through the cable. CAT-5 Wire - Output Binary Data RX Amp + High Speed Converter N Page: 1-16

9 Voiceband Digital Communications PCM Codec: Analog Transmitter Digital 0-4 khz 2 MHz 32 khz 16 khz 8 khz 8 khz 8 khz V in Anti-aliasing Active RC Filter Second Order Switched Cap. Σ Modulator Sinc Filter 3 rd Order First Halfband Filtert Second Halfband Filtert Sinc Droop Correction Filter µ/a law Compressor Interface V out Anti-aliasing Active RC Filter Second Order Switched Cap. Smoothing Filter Second Order Digital Σ Modulator Second Halfband Filtert First Halfband Filtert Sinc Drrop Correction Filter µ/a law Expander 0-4 khz 2 MHz 32 khz 16 khz 8 khz 8 khz 8 khz Receiver Page: 1-17 Smart Sensors Object Sensor Signal Conditioning Digital Signal Processing Target Actuator Signal Conditioning D/A Smart Sensor is a sensor with data acquisition and data processing Page: 1-18

10 Data Storage Hard Disk: The data stored on a compact disk (CD) and computer hard disk are binary signals. However, the signal generated by the read head is analog and corrupted with noise and distortion. As a result, the disk drive read channels requires lots of filtering and post processing. Analog signal from read head AGC Automatic Gain Control LPF Switched- Cap Filter Clock Generator Page: 1-19 Digital Imaging Camera Recorder: Today s imaging systems make use of extensive digital post processing. Images can be captured by charge-coupled devices (CCDs) or by advanced CMOS image sensors. Image voltage or current signal is digitized by an converter. Image Sensor Anti-Aliasing Filter -Image Stabilization -Luminance processing -Zoom and Focus Page: 1-20

11 Video Systems High-Definition Television (HDTV) Set-top Box: A digital set top box is used to deliver interactive video services to a TV set via cable, satellite, or network. The video signal (270MBPS) is compressed into 2-15 MBPS (MPEG2) bit stream and modulated to form the RF signal. The sampling speed of DAC must be MHz, and with a resolution of 8 to 10 bits. Network Interface Module Audio D/A V audio V in Tuner Demodulator MPEG2 DEMUX HDTV Decoder 3X Video D/A V video THS 8133/34 Page: 1-21 Test of Integrated Circuits Arbitrary Waveform Generator (AWG) : The test of analog and mixed signal circuits usually requires precision test signals. Therefore, an Arbitrary Waveform Generator (AWG) is needed. The main idea is to use to create a coded binary signal which contains the information of test signal. The desired signal can be obtained by filtering the bit stream of the coded signal. TMS320 C6x Interface 1-bit DAC Lowpass Filter Output Signal Page: 1-22

12 Motor Control Cost-Effective Drivers : AC induction motors are widely used because of its low cost, high reliability and high efficiency. Flexibility of makes it possible to accomplish complex nonlinear control [8]. Feedback parameters like current, voltage, and position can be sensed and converted to digital signals by the use of converters. After processing the analog command signals can be obtained by D/A converters. - Estimate the feedback Parameters - Algorithm of control 123 ADC DAC Power Amplifier Page: 1-23 Digital Control Display & Control Data Transmission Analog Feedback Signal Conditioning ADC Unit DAC Analog Amplifier Signal Conditioning Position Control Speed Control Page: 1-24

13 Data Converters for Telecom Application Year Supply Technology Bits fs Speech ISDN GSM OSR Type Area mm ± 5V 5 µ NMOS 8 8 khz Suc. Appro ± 5V 2.4 µ CMOS 12 1 MHz 256x V 1.2 µ CMOS 13 2 MHz 512x V 0.7 µ CMOS 14 2 MHz 512x V 2 µ CMOS MHz 128x V 0.5 µ CMOS MHz 128x V 1.2 µ CMOS khz 1x V 0.7 µ CMOS khz 1x V 0.5 µ CMOS MHz 24x ADSL V 0.7 µ CMOS MHz 24x V 0.5 µ CMOS MHz 4x VDSL V 0.35 µ CMOS MHz 1x 2 nd Order D/A 2 nd Order D/A 2 nd Order D/A 2 nd Order D/A 4 th order D 6 th order D D/A Suc. Appr. Binary Weig D/A Suc. Appr. Binary Weig D/A 4 th order D Bin.-Weig. D/A 4 th order D 6 th order D D/A Pipelined Switched-I D/A Pipelined Switched-I D/A Power mw Page: 1-25 Conclusions Target Applications: Wireless Communications xdsl Gigabit Ethernet Video Systems Page: 1-26

14 References and Further Reading [1] V. K. Garg and J. E. Wilkes, Principles and Applications of GSM, Prentice-Hall, [2] D. J. Rauschmayer, ADSL/VDSL Principles, Macmillan Technologies Publishing, [3] B. Razavi, RF Microelectronics, Prentice-Hall, [4] R. J. van de Plassche, Integrated Analog-to-Digital and Digitalto-Analog Converters. Kluwer Academic Publishers, [5] B. Razavi, Principles of Data Conversion System Design. IEEE Press, [6] G. W. Roberts and A. K. Lu, Analog Signal Generation for Built- In-Self-Test of Mixed-Signal Integrated Circuits, Kluwer Academic Publishers, Page: 1-27 References and Further Reading (cont.) [7] Texas Instruments, Providing the Right Solution for VDSL, Version 1.05, July [8] Texas Instruments, Solutions for Motor Control Using the TMS320f240 Controller, SPRA345, Page: 1-28