HO2_315aSP09_intro

HO2_315aSP09_intro - EE315A VLSI Signal Conditioning...

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Unformatted text preview: EE315A VLSI Signal Conditioning Circuits Boris Murmann Stanford University [email protected] Copyright © 2009 by Boris Murmann EE315A ― HO #2 B. Murmann 1 Mixed Signal System EE252 EE312 ... Analog Media and Transducers EE214 EE314 EE315A Signal Conditioning EE315B EE264 EE371 ... A/D Digital Processing Signal Conditioning D/A Sensors, Actuators, Antennas, Storage Media, ... B. Murmann EE315A ― HO #2 2 Signal Conditioning (′sig·nəl kən′dish·ən·iŋ) (communications) Processing the form or mode of a signal so as to make it intelligible to or compatible with a given device, such as a data transmission line, including such manipulation as pulse shaping, pulse clipping, digitizing, and linearizing. [www.answers.com] [www answers com] In electronics, signal conditioning means manipulating an analogue signal in such a way that it meets the requirements of the next stage for further processing. Signal conditioning can include amplification, filtering, converting, range matching isolation and any other processes required to make matching, sensor output suitable for processing after conditioning. [http://en.wikipedia.org] B. Murmann EE315A ― HO #2 3 Example: Cellular Phone B. Murmann EE315A ― HO #2 4 Example: Hard Disk Drive [Bloodworth, JSSC 11/1999] B. Murmann EE315A ― HO #2 5 Example: MEMS Accelerometer [Lemkin, JSSC 4/1999] B. Murmann EE315A ― HO #2 6 Example: Neural Field Potential Amplifier Electroencephalography (EEG) = recording of electrical activity along g y g the scalp produced by the firing of neurons within the brain [Avestruz, JSSC 12/2008] B. Murmann EE315A ― HO #2 7 Course Objective • Acquire a thorough understanding of the basic principles principles, challenges and limitations in signal conditioning circuit design – Focus on concepts that are unlikely to expire – Preparation for further study of state-of-the-art "fine-tuned" state of the art "fine tuned" realizations • Strategy – Acquire basic intuition by studying a selection of commonly used circuit and design techniques – Acquire depth through a design p j q p g g project that entails design, g , optimization and thorough characterization of a filter circuit in modern technology B. Murmann EE315A ― HO #2 8 Staff and Website • Teaching assistants – Ross Walker – Andy Chen • Administrative support – Ann Guerra, CIS 207 • Lecture videos are provided on the web, but please come to class to keep the discussion intercative • Web page: http://ccnet.stanford.edu/ee315a – Check regularly, especially the "bulletin board" section – Only enrolled students can register for ccnet access • We synchronize the ccnet database with axess.stanford.edu manually, ~ once per day during first week of instruction EE315A ― HO #2 B. Murmann 9 Preparation • Course prerequisites – EE214 or equivalent • Device physics and models • Transistor level analog circuits, elementary gain stages • Frequency response, feedback, noise response feedback – Prior exposure to Spice, Matlab – Basic signals and systems • L l Laplace and z-transforms d f • Please talk to me if you are not sure if you have the required background B. Murmann EE315A ― HO #2 10 Analog Circuit Sequence Fundamentals for upperlevel undergraduates and entry-level graduate students Analysis and design techniques for high highperformance circuits in advanced Technologies Design of application and function- specific function mixed-signal/RF building blocks EE314 — RF Integrated Circuit Design EE114 — Fundamentals of Analog Integrated Circuit Design EE214 — Advanced Analog Integrated Circuit Design EE315A — VLSI Signal Conditioning Circuits EE315B — VLSI Data Conversion Circuits B. Murmann EE315A ― HO #2 11 Assignments • Homework: (30%) ( %) – Handed out on Thu, due following Thu after lecture (1 pm) – Lowest HW score is dropped in final grade calculation • Project: (30%) – Design of a high performance filter circuit – Architecture design using idealized components g g p – Implementation of a critical sub-block at the transistor level – Project report in the format of an IEEE journal paper • Final Exam (40%) Fi l E B. Murmann EE315A ― HO #2 12 Honor Code • Please remember you are bound by the honor code y y – I will trust you not to cheat – I will try not to tempt you • But if you are found cheating it is very serious – There is a formal hearing – You can be thrown out of Stanford • Save yourself and me a huge hassle and be honest • For more info – http://www.stanford.edu/dept/vpsa/judicialaffairs/guiding/pdf/ honorcode.pdf B. Murmann EE315A ― HO #2 13 Tools and Technology • Primary tools – Cadence Virtuoso Schematic Editor – Cadence Virtuoso Analog Design Environment – Cadence SpectreRF simulator – You can use your own tools/setups “at own risk“ • Getting started – Read info on remote connection to our servers (see CAD section of course website) – Go through setup instructions under /usr/class/ee315a/GETTING_STARTED (text file) – Work through tutorial provided in HW1 • EE315A Technology – 0.18-μm CMOS – BSIM3v3 models provided under /usr/class/ee315a/models B. Murmann EE315A ― HO #2 14 Reference Books • Schauman and Van Valkenburg, Design of Analog Filters, Oxford University Press, 2001 • Gray, Hurst, Lewis and Meyer, Analysis and Design of Analog Integrated Circuits, 5th Edition, Wiley, 2008 • Allen and Holberg CMOS Analog Circuit Design 2nd Edition Holberg, Design, Edition, Oxford University Press, 2002 • Laker and Sansen, Design of Analog Integrated Circuits and Systems, M G S t McGraw-Hill, 1994 Hill • Gregorian & Temes, Analog MOS Integrated Circuits for Signal Processing, Wiley, 1986 g y • Williams and Taylor, Electronic Filter Design Handbook, 3rd edition, McGraw-Hill, 1995 • Zverev, Handbook of Filter Synthesis, Wiley, 1967 EE315A ― HO #2 B. Murmann 15 Course Topics • Continuous time filters – Biquad and ladder-based designs ladder based – Active-RC and Gm-C filters • Switched capacitor filters – A Approximation errors i i – Circuit simulation (periodic ac and noise analysis) • Design of Operational Transconductance Ampilfiers (OTAs) – Analysis and design of fully differential implementations – Gm/ID-based optimization (BW – noise – power dissipation) • Dynamic offset cancellation t h i D i ff t ll ti techniques • Sensor interface examples • Layout techniques B. Murmann EE315A ― HO #2 16 Acknowledgement • The course notes for EE315A borrow material that was originally g y prepared by – Bernhard Boser (EECS247, UC Berkeley) – Haideh Khorramabadi (EECS247, UC Berkeley) (EECS247 – Susan Luschas (Bosch Research) – Un-Ku Moon (ECE520, Oregon State University) B. Murmann EE315A ― HO #2 17 Introduction to Filters • Filtering – Frequency-selective signal processing – The most common type of signal processing – Examples • Extract desired signal from many ( g y (radio, etc.), anti-aliasing, , ), g, phase equalization, … • Engineering problem – Ideal filters are non causal or otherwise impractical non-causal – No global optimization techniques known – In practice, chose from several known solutions • Butterworth, Elliptic, Bessel, … – Filter design always requires a compromise between magnitude response, phase response, step response, complexity, … l i B. Murmann EE315A ― HO #2 18 Lowpass Filter Example EE315A ― HO #2 B. Murmann 19 First-Order RC Filter R H( s ) = B. Murmann Vout ( s ) 1 = Vin ( s ) 1 + s ω0 EE315A ― HO #2 C ω0 = 1 RC 20 Poles and Zeros H( s ) = N( s ) 1 = D( s ) 1 + s ωo jω s-plane s = σ + jω Pole Zero σ z→∞ -ωo In general, the “finite” poles and zeros follow from the roots of D(s) and N(s) – When the order (n) of N(s) is smaller than the order (d) of D(s), there will be zero(s) at infinity with multiplicity d-n ( ) y p y EE315A ― HO #2 B. Murmann 21 Magnitude Response 3 2.5 Magnitude [linear] • p = −ωo |H(s)| 2 1.5 1 0.5 0 5 5 x 10 5 0 0 5 x 10 Sigma [Hz] σ/2π B. Murmann -5 -5 EE315A ― HO #2 ω/2π Frequency [Hz] 22 Steady-State Magnitude and Phase • Evaluate H(s) for s=jω – Steady-state phasor analysis y p y H( j ω ) = 1 1 = 2 1 + j ωRC 1 + ( ωRC ) ∠H( j ω ) = tan −1 ( −ωRC ) • Magnitude and phase of the transfer function are commonly illustrated using Bode plots – Simply a log-log plot of the magnitude along with a log-angle plot for the phase EE114 (HO #9) B. Murmann 23 Bode Plot (1) At ω = 1/RC |H(jω )| [dB] 0 -20 Angle[H(jω )] [deg g] -40 -2 10 H( j ω ) = 10 -1 10 0 10 1 10 2 0 1 1 + (1) 2 1 2 = ⎛ 1 ⎞ 20 ⋅ log ⎜ ⎟ ≅ −3 [dB] ⎝ 2⎠ -50 ∠H( j ω ) = tan −1 ( −1) = −45° -100 -2 10 B. Murmann 10 -1 0 10 ω *RC 10 1 EE114 (HO #9) 10 2 24 Bode Plot (2) |H(jω )| [dB] 0 • -20 Angle[H(jω )] [deg g] -40 -2 10 10 -1 10 0 10 1 10 2 Asymptotic behavior – 20dB/decade magnitude roll-off – 90 degree phase change over 2 decades 0 H( j ω ) ω→0 = 1 -50 -100 -2 10 B. Murmann H( j ω ) ω→∞ = 0 10 -1 0 10 ω *RC 10 1 10 2 EE114 (HO #9) 25 Parasitics • Can we really get 100 dB attenuation at 10 GHz? yg – Probably not – Parasitics tend to limit the performance of analog components at high frequencies – For example • Shunt capacitance • Feed through capacitance Feed-through • Finite inductor, capacitor Q B. Murmann EE315A ― HO #2 26 RC Filter with Feedthrough Capacitance C R H( s ) = Pole 1 1 ≈− R (C + CP ) RC Zero 1 + sRCP RC 1 + sR (C + C P ) p=− z=− 1 RCP EE315A ― HO #2 B. Murmann 27 Bode Plot |H(jω )| [dB] [ 0 -20 -40 -60 Angle[H(jω )] [deg] 10 -2 10 10 2 10 4 10 6 0 -50 50 -100 -2 10 10 0 H( j ω ) ω→∞ = B. Murmann 0 2 10 ω *RC 10 4 CP C ≅ P = 10−3 = −60dB C + CP C EE315A ― HO #2 28 Parasitic Poles and Zeros • Analog p g passive components aren’t ideal p – Extra real poles/zeroes result from parasitics – Parasitic effects begin to appear “40-60 dB beyond” desired component characteristics – Common sense helps you anticipate them • The situation is similar in filters that involve active elements – You will always see extra poles and zeros, e.g. due to amplifier imperfections – We’ll look at these issues later… • Digital filters do not suffer from these effects EE315A ― HO #2 B. Murmann 29 Second-Order Lowpass Filter • Better attenuation (compared to first order) • Often implement complex poles (rather than multiple real ones) – Why? • General bi G l biquadratic (2nd order) t d ti d ) transfer function f f ti H( j ω ) ω= 0 = 1 1 H( s ) = 1+ s s2 + 2 ωPQP ωP H( j ω ) ω→∞ = 0 H( j ω ) ω=ω = QP P B. Murmann EE315A ― HO #2 30 Magnitude Response 3 Magnitude [linea ar] 2.5 |H(s)| 2 1.5 1 0.5 05 ωP = 2π × 100kHz 0 2 QP = 10 1 x 10 2 1 0 5 0 -1 Sigma [Hz] σ/2π -2 -2 ω/2π Frequency [Hz] EE315A ― HO #2 B. Murmann 5 x 10 -1 31 Biquad Poles H( s ) = has poles at for f B. Murmann 1 s s2 1+ + 2 ωPQP ωP s=− QP ≤ 1 2 ( ωP 2 1 ± 1 − 4QP 2QP ) poles are real, complex otherwise l l l th i EE315A ― HO #2 32 Complex Poles QP > 1 2 ⇒ s1,2 = − ( ωP 2 1 ± j 4QP − 1 2QP ) Distance from origin in s-plane 2 ⎛ ω ⎞ 2 2 d = ⎜ P ⎟ 1 + 4QP − 1 = ωP ⎝ 2QP ⎠ 2 ( ) EE315A ― HO #2 B. Murmann 33 s-Plane jω r = ωP r Re = - α σ Re B. Murmann ωP 2QP ⎛ 1 ⎞ α = cos −1 ⎜ ⎟ ⎝ 2QP ⎠ EE315A ― HO #2 34 M Magnitude [dB] Bode Plot 20 0 -20 -40 -60 -80 2 10 -40 dB/dec 10 3 10 4 10 5 10 6 10 7 Ph hase [deg] f [Hz] 0 -50 -180o -100 -150 10 2 10 3 10 4 10 5 10 6 10 7 f [Hz] EE315A ― HO #2 B. Murmann 35 Matlab Code % Bode plot of second order lowpass figure(1); clear all; subplot(2, 1, 1) semilogx(f, magdb, linewidth semilogx(f magdb 'linewidth', 2); fp = 100e3; set(gca, 'fontsize', 14); Qp = 10; xlabel('f [Hz]') f = logspace(2, 7, 1000); ylabel('Magnitude [dB]'); s = tf('s'); axis([min(f) max(f) -80 max(magdb)+5]) wp = 2*pi*fp; grid; h = 1 / (1 + s/wp/Qp + s^2/wp^2); subplot(2, 1, 2) [mag, phase] = bode(h, 2*pi*f); semilogx(f, angle, 'linewidth', 2); n = length(f); set(gca, 'fontsize', 14); magdb =20*log10(reshape(mag 1 n)); =20*log10(reshape(mag, 1, xlabel('f [Hz]') angle =reshape(phase, 1, n); ylabel('Phase [deg]'); axis([min(f) max(f) -190 10]) g grid; B. Murmann EE315A ― HO #2 36 Varying Q Magnitude Qp=0 5 =0.5 30 M Magnitude [dB B] 40 Q =10 20 Qp=100 p 10 H( j ω ) ω=ω = QP 0 P -10 -20 -30 -40 4 10 5 10 f [Hz] 10 6 EE315A ― HO #2 B. Murmann Varying Q 0 37 Phase Q =0.5 05 p Qp=10 Qp=100 P Phase [deg] -50 Slope of phase at ωp is given by -45°/decade ⋅ Qp -100 -150 10 4 B. Murmann 5 10 f [Hz] 10 EE315A ― HO #2 6 38 Aside – Making a Plot for a Publication figure(1); subplot(2, 1, 2) subplot(2, 1, subplot(2 1 1) semilogx(f, angle, k semilogx(f angle 'k', 'linewidth', 2); linewidth semilogx(f, magdb, 'k', 'linewidth', 2); set(gca, 'fontsize', 9); set(gca, 'fontsize', 9); set(gca,'FontName','Times'); set(gca,'FontName','Times'); s = sprintf('f [Hz]\n(b)') s = sprintf('f [Hz]\n(a)') xlabel(s); xlabel(s); ylabel('Phase [deg]'); ylabel('Magnitude [dB]'); axis([min(f) max(f) -190 10]) axis([min(f) max(f) -80 max(magdb)+5]) grid; grid; set(1, 'Units', 'inches'); % columns are 3.5 inches wide 3 5 set(1, 'Position', [6 4 3.5 5]); set(1, 'PaperPositionMode', 'auto'); p print -dtiff -r600 -f1 fig1.tif; g B. Murmann EE315A ― HO #2 39 TIFF Output Embedded in Template Publication templates: http://www.ieee.org/web/ publications/authors/transjnl/ bli ti / th /t j l/ B. Murmann EE315A ― HO #2 40 ...
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This note was uploaded on 08/13/2009 for the course EE 315 taught by Professor Borismurmann during the Spring '09 term at Stanford.

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