1. 2009. 03. 임한조 아주대학교 전자공학부 hanjolim@ajou.ac.kr
전자 회로 1 Lecture 1
임한조
아주대학교 전자공학부
이 강의 노트는 전자공학부 곽노준 교수께서 08.03에 작성한 것으로 노트제공에 감사드림.

2. Overview Review of basic electric circuit Introduction to Amplifiers
Resistor, capacitor, inductor
Current and voltage source (Norton/Thevenin form)
Frequency response (single time constant)
Introduction to Amplifiers
Gain
Transfer characteristics
Introduction to Inverters
Noise margin
Propagation delay
Some materials in this note are from
Lecture notes of Prof. Woodward Yang (Harvard U.)
Lecture notes of Prof. Sang-Bae Kim (Ajou U.)
March, 2008
Nojun Kwak

3. Review of Circuit Basics
Some basic circuit elements that will be used extensively in this class.
March, 2008
Nojun Kwak

4. Capacitor Has memory/hysterisis Terminal relationship
Stores charges on electrodes (parallel plates)
Energy stored in electric field
Capacitance measured in units of Farads (F)
Range of typical values (1pF ~ 1000uF)
Capacitor types
Ceramic (pF)
Mylar (nF)
Electrolytic (uF)
Remember
At LF, C is open circuit
At HF, C is closed circuit
March, 2008
Nojun Kwak

5. Inductor Has memory/hysterisis Terminal relationship
Energy stored in magnetic field
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

6. Impedance (driven by sinusoidal source)
March, 2008
Nojun Kwak

7. Representation of Signal Source
Thevenin form
Norton form
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

8. Analog vs. Digital Signal
Analog Signal
Discrete Sampled Signal
Analog-to-Digital Converter
111
101
Digital Signal
March, 2008
Nojun Kwak

9. Time & Frequency Domain
Amplitude
(power) f t
Frequency domain
(frequency spectrum)
Time domain
Fourier series
Time and Frequency-Domain Representation of Analog Signals
March, 2008
Nojun Kwak

10. Frequency response (single time constant)
March, 2008
Nojun Kwak

11. Bode plots
Low pass
High pass
March, 2008
Nojun Kwak

12. 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

13. 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

14. Amp. with Power Supplies (How Po > Pi ?)
Efficiency:
Because PI is normally very small
March, 2008
Nojun Kwak

15. Transfer characteristic w/ Saturation
To operate linearly:
March, 2008
Nojun Kwak

16. Nonlinearity and Biasing
Small-signal gain (Av) = slope of the transfer curve at the operation point
March, 2008
Nojun Kwak

17. Circuit models for Amps
March, 2008
Nojun Kwak

18. Voltage amplifiers
To make Vo/Vs large (regardless of source and load),
 Ri  should be large
Ro  should be small
March, 2008
Nojun Kwak

19. 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.
Large input resistance
Small output resistance
High gain
March, 2008
Nojun Kwak

20. Example: BJT (small signal model)
Common emitter amplifier
March, 2008
Nojun Kwak

21. Frequency response of an amp.
March, 2008
Nojun Kwak

22. Inverter (mostly for Digital Circuits)
Logic inverter symbol
Ideal Logic Inverter
Real Logic Inverter (with linear approx.)
March, 2008
Nojun Kwak

23. Implementation of Inverters
Voltage controlled switch
Vi = low  (b)
Vi = high  (c)
March, 2008
Nojun Kwak

24. Inverter with CMOS
CMOS – can be interpreted as a pair of complementary switches
March, 2008
Nojun Kwak

25. Propagation delay of an inverter
March, 2008
Nojun Kwak