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EECS240 – Spring 2013

Advanced Analog Integrated Circuits Lecture 1: Introduction

Lingkai Kong EECS

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Who am I? •  Lingkai Kong •  Ph.D. in EECS, UC Berkeley, Dec. 2012.

•  Currently a post-doc at BWRC

•  Thesis: 60GHz Energy-Efficient Phased-Array Design for High Data-Rate Wireless Communications

•  Research Interest •  Mixed-signal circuit and system design •  RF/Microwave circuit and system design •  Power circuit design •  Design Automation

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Teaching Staff •  Lingkai’s office hours

•  Location: TBA •  Tues. and Thurs. 11am-12pm (right after the class) •  konglk@eecs

•  GSI: Yue Lu •  Weekly discussion session/office hours •  Time/location: TBA

•  Most likely Fri. 10am-11am in 550 Cory •  yuelu@eecs

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Administrative •  Course web page:

http://bwrc.eecs.berkeley.edu/classes/icdesign/ee240_sp13

•  Lecture videos •  Will be posted on course website

•  All announcements made through piazza •  Enroll in EE240 at:

https://piazza.com/class#spring2013/ee240

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Lecture Notes •  Based on material from Prof. Elad Alon, Prof.

Bernhard Boser, Prof. Ali Niknejad, Simone Gambini, and myself

•  Primary source of material for the class •  No required text – reference texts on next slide

•  Notes posted on the web at least 1 hour before lecture

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References •  Analysis and Design of Integrated Circuits,

Paul R. Gray, Paul J. Hurst, Stephen H. Lewis, Robert G. Meyer, 4th Ed., Wiley, 2001.

•  Design of Analog CMOS Integrated Circuits, Behzad Razavi, McGraw-Hill, 2000.

•  The Design of CMOS Radio-Frequency Integrated Circuits, Thomas H. Lee, 2nd Ed., Cambridge University Press, 2003.

•  The Art of Analog Layout, A. Hastings, Prentice Hall, 2005.

•  The Designers Guide to SPICE & SPECTRE, K. S. Kundert, Kluwer Academic Press, 1995.

•  Operation and Modeling of the MOS Transistor, Y. Tsividis, McGraw-Hill, 2nd Edition, 1999.

•  Solid-State Circuits, Journey of

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Grading •  Grading:

•  HW: 20% •  One HW roughly every two weeks •  Essential for learning the class material

•  Project: 25% •  Groups of 2 – find a partner ahead of time

•  Midterm: 20% •  Final Exam: 35%

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Homework •  Homework:

•  Can discuss/work together •  But write-up must be individual •  Hand in during the class •  Electronic version encouraged •  Generally due 5pm on Thursdays

•  No late submissions in general •  Start early! •  Exceptions: Tape-out and etc., tell us ahead of

time

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Simulation Tools •  Need to setup Spectre or equivalent

simulator •  HSPICE, ADS, BDA, SpectreRF, Eldo, or other

favorite tool •  Berkeley Analog Generator (BAG)

•  Python based analog design framework •  Design automation/scripting •  Design optimization •  Complete setup on instructional servers (t7400-*)

and BWRC servers •  See course website for tutorials •  Special discussion session for BAG (this Fri.)

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Schedule Notes •  ISSCC Week: 2/17 – 2/21 (no lectures) •  Spring break: 3/25 – 3/29 •  Midterm: March 14 (tentative) •  Project:

•  Part 1 due middle of Apr. •  Part 2 due end of Apr. •  Part 3 due May 9th(tentative)

•  Final: Wed., May 15, 11:30am-2:30pm

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Why Analog IC?

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“Analog ICs in a Digital World?” Digital circuitry: •  Cost/function

decreases by 29% each year

•  30X in 10 years

Analog circuitry: •  Cost/function may not scale very well •  Common complaints about scaling analog:

•  Supply voltage is too low, device gain is low, horrible matching…

“Analog will die – everything will be digital!” •  Who agrees?

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Fabrication cost per transistor

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(Good) Digital Design Needs Analog Insights •  Can synthesize large blocks at “medium”

frequencies in ASIC flow, but •  Need to know transistors to design the cells •  Really need to know transistors to design memories

•  Lots of analog issues to deal with when push digital performance, power, etc. •  Charge sharing, interconnect parasitics, etc.

•  Matching growing concern in advanced CMOS technologies •  Especially in memories

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Another Example

•  Look at interface between two digital chips •  Is received bit a

“1” or a “0”?

•  Analog circuits critical for receiving bits correctly

TX RX

Initial eye

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The More Fundamental Reason •  The “real” or “physical” world is analog

•  Analog is required to interface to just about anything

•  Digital signals have analog characteristics too… •  “If you look close enough, all the digital signals are

analog” •  In many applications, analog is in the critical path

•  Examples: •  Wireline, optical communications •  RF transceivers (receiver + transmitter) •  Sensors and actuators (e.g., MEMS)

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RF Receiver

•  Why so many RF and analog building blocks?

•  Why not just put the ADC right after the antenna?

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Software Defined Radio

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RF Transceiver Layout

•  Analog building blocks take up significant die area •  Even in 0.13um…

Source: Zagari et al, “A Dual-Band CMOS MIMO Radio SoC for IEEE 802.11n Wireless LAN”, JSSC Dec. 2008"

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Capacitive Touch Sensor

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MEMS Accelerometer

DSP"

A/D Conversion"

Amplification"

C/V conversion"

MEMS "sensor"

Acceleration"

Digital Output"

M. Lemkin and B. E. Boser, “A Three-Axis Micromachined Accelerometer with a CMOS Position-Sense Interface and Digital Offset-Trim Electronics,” IEEE J. Solid-State Circuits, vol. SC-34, pp. 456-468, April 1999

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Analog Design versus Others

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Analog versus Digital Design •  Abstraction in digital is Boolean logic (1’s, 0’s)

•  Works because of noise margins •  At a higher level, it’s gates and registers (RTL) •  Digital layout is often automated

•  Abstraction in analog is the device model •  (BSIM is a few thousand lines long)

•  At a higher level, it’s the (opamps) (filters) (comparators) •  Abstraction depends on the problem you’re solving

•  Analog layout is usually hand crafted •  Is there a way to automate analog layout?

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Analog versus RF Design •  RF = “Analog with inductors” •  RF signal is usually narrowband (i.e., sinusoidal)

•  Tuned circuit techniques used for signal processing.

•  RF impedance levels are relatively low •  Can’t make transmission line impedance too high

•  Analog impedances are high (low) for voltage (current) gain. •  Voltage/current gain versus power gain.

•  “Mixed-signal” analog is often discrete time (sampled).

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RF Shifting Toward Analog

•  Classic RF uses inductors to tune the circuits •  Inductors are big – would be nice to get rid of them

•  With increasing fT , moving towards wideband analog & feedback •  What’s the penalty?

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Mixed-Signal Design

•  Many building blocks involve analog and digital circuit co-design •  PLLs, ADCs, etc.

•  Sometimes hard to even distinguish between analog and digital •  Is VCO analog, or digital?

Clk

PFD RegulatorVcp

Vreg

up

down

÷N

Ref_clk+

-

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Digitally-Assisted Analog

•  In 90nm, one RF inductor (200µ× 200µ) takes same area as a microprocessor! •  Leverage digital processing to improve analog circuits

•  Good analog design doesn’t go away though •  Need to find right partitioning to maximize the benefit

Source: B. Murmann, “Digitally-Assisted Analog Circuits – A Motivational Overview,” ISSCC 2007."

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Contents of This Class

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Syllabus •  Devices (both passive and active):

•  Models, simulation, layout, and matching •  Electronic noise •  Basic support functions:

•  Current sources, references, biasing •  Basic analog “gate”: amplifier

•  Opamps, OTAs, feedback, settling time, common-mode feedback

•  Application driver •  Motivates additional building blocks •  As well as why you care about certain specs

•  Data converters, comparators, offset cancellation, filters, sample & hold, oscillators, PLLs

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Course Focus •  Focus is on analog design

•  Typically: Specs circuit topology layout

•  Spec-driven approach

•  Where specs come from

•  Key point: •  Especially in analog, some things are much

“easier” to do than others •  Sometimes (often) the right thing to do is

change the specs

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Course Goal •  Learn how to create systematic approaches

to analog design •  Based on fundamental principles •  For a wide variety of applications

•  Will show specific design methodology example •  OTA designs embedded in ADCs

•  And then move on to a more complex system

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EECS 240 versus 247 •  EECS 240

•  Transistor level building blocks •  Device and circuit fundamentals •  A lot of the class at a low level of abstraction

•  SPICE

•  EECS 247 •  Macro-models, behavioral simulation, large

systems •  Signal processing fundamentals •  High level of abstraction •  Matlab

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240 versus 242/142 •  142/242 mostly concerned with narrowband

circuits operating at a “high” carrier frequency •  Signals mostly look like sinusoids •  Inductors ubiquitous •  Use of feedback is rare

•  240 focuses on more “wideband”, general-purpose analog and mixed-signal •  Signals are “arbitrary” •  Spend a lot of time worrying about capacitance •  Feedback common

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240 versus 231 •  231 concentrates on device physics

•  240: device physics abstracted to the extent possible •  Device models from a “circuit designer’s perspective” •  Treat transistor as black box described by complex

equations •  Equations relevant for biasing, nonlinear effects

(output swing), and some charge storage effects •  Mostly outside design loop •  “small signal analysis”