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전자 회로 1 Lecture 1 2009. 03. 임한조 아주대학교 전자공학부 [email protected] 이 강의 노트는 전자공학부 곽노준 교수께서 08.03에 작성한 것으로 노트제공에 감사드림. Overview Review of basic electric circuit Introduction to Amplifiers Gain Transfer characteristics Introduction to Inverters • Resistor, capacitor, inductor Current and voltage source (Norton/Thevenin form) Frequency response (single time constant) Noise margin Propagation delay Some materials in this note are from • Lecture notes of Prof. Woodward Yang (Harvard U.) • • March, 2008 http://www.deas.harvard.edu/courses/es154 Lecture notes of Prof. Sang-Bae Kim (Ajou U.) Nojun Kwak 2 Review of Circuit Basics Some basic circuit elements that will be used extensively in this class. March, 2008 Nojun Kwak 3 Capacitor Has memory/hysterisis Terminal relationship Stores charges on electrodes (parallel plates) qc (t ) Cvc (t ) Energy stored in electric field U (t ) t 0 ic vc dt t 0 C dvc (t ) 1 2 vc (t ) dt Cvc (t ) dt 2 Capacitance measured in units of Farads (F) Range of typical values (1pF ~ 1000uF) Capacitor types Remember Ceramic (pF) • At LF, C is open circuit Mylar (nF) • At HF, C is closed circuit March, 2008 Electrolytic (uF) Nojun Kwak 4 Inductor Has memory/hysterisis Terminal relationship Energy stored in magnetic field t t 0 0 U (t ) iL vL dt LiL (t ) diL (t ) 1 2 dt LiL (t ) dt 2 Inductance measured in units of Henries (H) Range of typical values (1uH ~ 1H) Remember • At LF, L is closed circuit • At HF, L is open circuit March, 2008 Nojun Kwak 5 Impedance (driven by sinusoidal source) March, 2008 Nojun Kwak 6 Representation of Signal Source Thevenin form Norton form s ( t ) Rs is ( t ) The two are equivalent. However (a) is preferred when Rs is small, small voltage drop While (b) is preferred when Rs is large. small current loss March, 2008 Nojun Kwak 7 Analog vs. Digital Signal Analog Signal Analog-to-Digital Converter Discrete Sampled Signal 111 111 101 Digital Signal March, 2008 Nojun Kwak 8 Time & Frequency Domain Time and Frequency-Domain Representation of Analog Signals Amplitude (power) f t t March, 2008 Nojun Kwak 9 Frequency response (single time constant) March, 2008 Nojun Kwak 10 Bode plots High pass Low pass March, 2008 Nojun Kwak 11 Amplifiers (mostly for Analog Circuits) Voltage amplifiers Current amplifiers Power amplifiers 4 ports 3 ports (common ground) The role of DC power supplies March, 2008 Nojun Kwak 12 Gains Voltage Gain: Av = vo / vi Current Gain: Ai = io / ii Power Gain: Ap = Po / Pi = vo io /vi ii = Av Ai Gain in dB (decibel) Voltage, Current gain = 20 log (Av, Ai) Power gain = 10 log (Ap) Ap (dB) = ½ [Av (dB) + Ai (dB)] * For more information, consult App. B. March, 2008 Nojun Kwak 13 Amp. with Power Supplies (How Po > Pi ?) Pdc V1 I1 + V2 I 2 Efficiency: Pdc + PI PL + Pdissipated PL 100 Pdc (1.10) Because PI is normally very small March, 2008 Nojun Kwak 14 Transfer characteristic w/ Saturation To operate linearly: L L I A A March, 2008 Nojun Kwak 15 Nonlinearity and Biasing I ( t ) VI + i ( t ) 0 (t ) V0 + 0 ( t ) I ( t ) A i ( t ) A = d d at Q Small-signal gain (Av) = slope of the transfer curve at the operation point March, 2008 Nojun Kwak 16 Circuit models for Amps March, 2008 Nojun Kwak 17 Voltage amplifiers RL A oi RL R Ri i s Ri Rs RL A A o i RL R0 (1.13) (1.12) 0 Ri RL A o s Ri Rs RL R0 To make Vo/Vs large (regardless of source and load), Ri should be large Ro should be small March, 2008 Nojun Kwak 18 Example: multistage voltage amps. Cascade or multi-stage amplifier: input resistance of an amplifier stage acts as a load to the previous stage. Typically used for Op-amp. e.g. 741 type Desirable characteristics for a voltage amp. March, 2008 Large input resistance Small output resistance High gain Nojun Kwak 19 Example: BJT (small signal model) Common emitter amplifier March, 2008 Nojun Kwak 20 Frequency response of an amp. Vo T ( ) Vi T ( ) March, 2008 Nojun Kwak 21 Inverter (mostly for Digital Circuits) Logic inverter symbol NH H NM L VDD /2 Ideal Logic Inverter March, 2008 NH H VOH VIH NM L VIL VOL (1.27) (1.25) (1.26) Real Logic Inverter (with linear approx.) Nojun Kwak 22 Implementation of Inverters Voltage controlled switch Vi = low (b) Vi = high (c) March, 2008 Nojun Kwak 23 Inverter with CMOS CMOS – can be interpreted as a pair of complementary switches March, 2008 Nojun Kwak 24 Propagation delay of an inverter March, 2008 Nojun Kwak 25