EE247 Lecture 27 Term project student presentations Acknowledgements Examples of systems utilizing analogdigital interface circuitry not part of final exam self study EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 1 Administrative Office hours on Frid Dec 12th 3 to 4 30pm 477 Cory No office hours Thurs Dec 11th Questions can be asked via email EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 2 Term Project Presentations Ping Chen James Rikky Chintan Jiash Maryam Nam Seog Jungdong Lingkai Thura Lauren Mervin Abhinav Jason Lu Ye EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 3 Acknowledgements The course notes for EE247 are based on numerous sources including Prof P Gray s EE290 course Prof B Boser s EE247 course notes Prof B Murmann s Nyquist ADC notes Fall 2004 05 06 07 EE247 class feedback Last but not least Fall 2008 EE247 class The instructor would like to thank the class of 2008 for their enthusiastic active participation EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 4 Material Covered in EE247 Filters Continuous time filters Biquads ladder type filters Opamp RC Opamp MOSFET C gm C filters Automatic frequency tuning Switched capacitor SC filters Data Converters D A converter architectures A D converter Nyquist rate ADC Flash Interpolating Folding Pipeline ADCs Self calibration techniques Oversampled converters EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 5 Systems Including Analog Digital Interface Circuitry Not Included in Final Exam Wireline communications Telephone related DSL ISDN CODEC Television circuitry Cable modems TV tuners Ethernet 10 1Gigabit 10 100BaseT Wireless Cellular telephone CDMA Analog GSM Wireless LAN Blue tooth 802 11a b g Radio analog digital Television Disk drives Fiber optic systems EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 6 E E Circuit Course vs Frequency Range RF Band 500kHz 100GHz IF Band 455kHz AM Radio 10 7MHz 80MHz FM Radio Cellular Phone 100MHz Baseband DC 500MHz EE240 EE247 EE242 EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 7 Wireline Communications Telephone Based EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 8 Data Transmission Over Existing Twisted Pair Phone Lines Backbone Digital Network Central Office Xmitter Customer Twisted Pair Xmitter Receiver Receiver 3 to 5km POTS Data transmitted over existing phone lines covering distances close to 3 5miles Voice band MODEMs up to 56Kb s ISDN 160Kb s HDSL SDSL ADSL up to 8Mb s EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 9 Data Transmission Over Twisted Pair Phone Lines ISDN U Interface Transceiver Backbone Digital Network Central Office Xmitter Customer Twisted Pair Xmitter Receiver Receiver 3 to 5km POTS Full duplex transmission RX TX signals sent simultaneously 160kbit sec baseband data 80kHz signal bandwidth Standardized line code 2B1Q 4 level code 3 1 1 3 Max desired loop coverage 18kft 36dB signal attenuation Final required BER bit error rate 10 7 min SNDR 27dB EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 10 ISDN U Interface Transceiver Echo Problem Central Office Customer Xmitter Xmitter Receiver Receiver Transformer coupling to line For a perfectly matched system no leakage of TX signal into RX path Unfortunately system has poor matching complicating factor of bridgedtaps Bridged Tap Problem EECS 247 Lecture 27 Open Line Term Project Presentation Final Remarks 2008 H K Page 11 ISDN U Interface Transceiver Echo Problem Central Office Customer Xmitter Xmitter Receiver Receiver System full duplex transmission RX TX signals sent simultaneous at the same frequency band Leakage of TX signal to RX path echo Worst case echo could be 30dB higher compared to the received signal EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 12 ISDN U Interface Transceiver Echo Cancellation Echo cancellation performed in the digital domain Typically echo cancellation performed by transversal adaptive digital filter Any non linearity incurred by the analog circuitry makes echo canceller significantly more complex Desirable to have high linearity analog circuitry 75dB range EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 13 Simplified Transceiver Block Diagram CMA Control maintenance access unit DFE Decision feedback equalizer DEC Decimation filter REC Reconstruction filter LEC NEC Linear non linear echo canceller Ref H Khorramabadi et al An ANSI standard ISDN transceiver chip set IEEE International Solid State Circuits Conference vol XXXII pp 256 257 February 1989 EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 14 Analog Front End 2b S C DAC 2nd order Butterworth S C Filter Class A B Line Driver 13bit 2nd Order To avoid stringent requirements for nonlinear echo canceller high linearity analog circuitry needed 75dB EECS 247 Lecture 27 Peak signal frequency 80kHz Term Project Presentation Final Remarks 2008 H K Page 15 Data Transmission Over Twisted Pair Phone Lines DSL Digital Subscriber Loop Backbone Digital Network Central Office Xmitter Customer Twisted Pair Xmitter Receiver Receiver 3 to 5km POTS HDSL SDSL more like ISDN higher frequencies Full duplex transmission with RX TX signals on the same frequency band EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 16 Data Transmission Over Twisted Pair Phone Lines ADSL Asymmetric Digital Subscriber Loop Backbone Digital Network Central Office Customer Xmitter Xmitter Receiver Receiver POTS In USA mostly ADSL FDM frequency division multiplex Signal from CO to customer on a different band compared to customer to CO Echo cancellation can be performed by simple filtering Data rates up to 8Mbps much higher compared to ISDN EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 17 ADSL Signal Characteristics Main difference compared to ISDN TX RX signals on different frequency bands Downstream fast from CO to customer 138kHz to 1 1MHz Upstream slow from customer to CO 30kHz to 138kHz Echo cancellation much easier More severe signal attenuation at high frequencies 1MHz DSL v s 80kHz ISDN EECS 247 Lecture 27 Term Project Presentation Final Remarks 2008 H K Page 18 Typical ADSL Analog Front End Central Office Customer Premise ADC 16 14b with 14bit linearity pipeline with auto
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