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Berkeley ELENG 247A - Lecture 27

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EECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 1EE247Lecture 27• Term project student presentations• Acknowledgements• Examples of systems utilizing analog-digital interface circuitry (not part of final exam - self study)EECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 2Administrative• Office hours on Frid. Dec. 12th, 3 to 4:30pm @ 477 Cory• No office hours Thurs. Dec. 11th• Questions can be asked via emailEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 3Term Project Presentations• Ping-Chen & James• Rikky & Chintan• Jiash & Maryam• Nam-Seog & Jungdong• Kyoohyun & Kwangmo• Lingkai & Thura• Lauren & Mervin• Abhinav & Jason• Lu Ye EECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 4Acknowledgements• 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 5Material 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 convertersEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 6Systems 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 systemsEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 7E.E. Circuit Coursevs. Frequency RangeDC500MHzBasebandIF BandRF Band455kHz100MHz500kHz100GHz10.7MHz 80MHzAM Radio FM Radio Cellular PhoneEE240, EE247EE242EECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 8Wireline CommunicationsTelephone BasedEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 9Data Transmission Over Existing Twisted-Pair Phone LinesXmitterReceiverCentral OfficeBackboneDigital NetworkPOTSXmitterReceiver• 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)CustomerTwisted Pair3 to 5kmEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 10Data Transmission Over Twisted-Pair Phone LinesISDN (U-Interface) Transceiver• 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) 10-7Æ (min. SNDR=27dB)XmitterReceiverCentral OfficeBackboneDigital NetworkPOTSXmitterReceiverCustomerTwisted Pair3 to 5kmEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 11ISDN (U-Interface) TransceiverEcho ProblemCentral Office• Transformer coupling to line– For a perfectly matched system Æ no leakage of TX signal into RX path– Unfortunately, system has poor matching + complicating factor of bridged-tapsCustomerXmitterReceiverXmitterReceiverOpenLineBridgedTapProblemEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 12ISDN (U-Interface) TransceiverEcho ProblemCentral Office• System full duplex transmission Æ RX & TX signals sent simultaneous (& at the same frequency band)– Leakage of TX signal to RX path (echo)– Worst case Æ echo could be 30dB higher compared to the received signal!! CustomerXmitterReceiverXmitterReceiverEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 13ISDN (U-Interface) TransceiverEcho 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 Æ Desirable to have high linearity analog circuitry (75dB range)EECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 14Simplified Transceiver Block DiagramCMA Æ Control, maintenance & access unitDFE Æ Decision feedback equalizerDEC Æ Decimation filterREC Æ Reconstruction filterLEC & NEC ÆLinear/non-linear echo-cancellerRef: H. Khorramabadi, et. al"An ANSI standard ISDN transceiver chip set, " IEEE International Solid-State Circuits Conference, vol. XXXII, pp. 256 - 257, February 1989EECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 15Analog Front-End2b S.C.DAC2ndorderButterworthS.C. FilterClass A/BLine Driver13bit2ndOrderTo avoid stringent requirements for non-linear echo canceller:Æ high linearity analog circuitry needed (~ 75dB)Peak signal frequency Æ80kHzEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 16Data Transmission Over Twisted-Pair Phone LinesDSL (Digital Subscriber Loop)• HDSL &SDSL more like ISDN @ higher frequencies– Full duplex transmission with RX & TX signals on the same frequency bandXmitterReceiverCentral OfficeBackboneDigital NetworkPOTSXmitterReceiverCustomerTwisted Pair3 to 5kmEECS 247 Lecture 27: Term Project Presentation & Final Remarks © 2008 H. K. Page 17Data Transmission Over Twisted-Pair Phone LinesADSL (Asymmetric


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Berkeley ELENG 247A - Lecture 27

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