lecture14_ee689_noise_sources

lecture14_ee689_noise_sources - Sam Palermo Analog...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Sam Palermo Analog & Mixed-Signal Center Texas A&M University ECEN689: Special Topics in High-Speed Links Circuits and Systems Spring 2011 Lecture 14: Noise Sources Agenda Noise source overview Common noise sources Noise budgeting References Dally Ch 6 Stateye paper posted on website 2 Noise in High-Speed Link Systems Multiple noise sources can degrade link timing and amplitude margin 3 [ Dally ] Noise Source Overview Common noise sources Power supply noise Receiver offset Crosstalk Inter-symbol interference Random noise Power supply noise Switching current through finite supply impedance causes supply voltage drops that vary with time and physical location Receiver offset Caused by random device mismatches 4 Crosstalk One signal (aggressor) interfering with another signal (victim) On-chip coupling (capacitive) Off-chip coupling (t-line) Near-end Far-end Inter-symbol interference Signal dispersion causes signal to interfere with itself Random noise Thermal & shot noise Clock jitter components Bounded and Statistical Noise Sources Bounded or deterministic noise sources Have theoretically predictable values with defined worst-case bounds Allows for simple (but pessimistic) worst-case analysis Examples Crosstalk to small channel count ISI Receiver offset 5 Statistical or random noise sources Treat noise as a random process Source may be psuedo-random Often characterized w/ Gaussian stats RMS value Probability density function (PDF) Examples Thermal noise Clock jitter components Crosstalk to large channel count Understanding whether noise source is bounded or random is critical to accurate link performance estimation Proportional and Independent Noise Sources Some noise is proportional to signal swing Crosstalk Simultaneous switching power supply noise ISI Cant overpower this noise Larger signal = more noise 6 Some noise is independent to signal swing RX offset Non-IO power supply noise Can overpower this noise NI S N N V V K V + = Total noise Proportional noise constant Signal swing Independent noise Common Noise Sources Power supply noise Receiver offset Crosstalk Inter-symbol interference Random noise 7 Power Supply Noise Circuits draw current from the VDD supply nets and return current to the GND nets Supply networks have finite impedance Time-varying (switching) currents induce variations on the supply voltage Supply noise a circuit sees depends on its location in supply distribution network 8 [ Hodges ] Power Routing 9 Bad Block B will experience excessive supply noise Better Block B will experience 1/2 supply noise, but at the cost of double the power routing through blocks Even Better Block A & B will experience similar supply noise Best Block A & B are more isolated [ Hodges ] [ Hodges ] Supply Induced Delay Variation...
View Full Document

This note was uploaded on 01/01/2012 for the course ECEN 689 taught by Professor Enjeti during the Spring '07 term at Texas A&M.

Page1 / 46

lecture14_ee689_noise_sources - Sam Palermo Analog...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online