Microsoft PowerPoint - ch03ysk2012.ppt [호환 모드]

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1 전자회로 Ch3 iode Models and Circuits 김영석 충북대학교전자정보대학 k Ch3-1

2 Ch3 iode Models and Circuits 3.1 Ideal iode 3.2 PN Junction as a iode 3.4 Large Signal and Small-Signal Operation 3.5 Application of iodes Ch3-2

3 3.1 Ideal iode I Characteristics R = 0 I R = I = R = R = = 0 Ch3-3

4 Ex 1 When in is less than zero, the diode opens, so out = in. When in is greater than zero, the diode shorts, so out = 0. Ch3-4

5 Ex2: Rectifier A rectifier is a device that t passes positive-half cycle of a sinusoid and blocks the negative half-cycle or vice versa. When in is greater than 0, diode shorts, so out = in ; however, when in is less than 0, diode opens, no current flows thru R 1, out = I R1 R 1 = 0. Ch3-5

6 3.2 PN Junction as a iode: ifferent Models So far we have studied the ideal model of diode. However, there are still the exponential and constant voltage models. Ch3-6

7 Input/Output Characteristics with Ideal and Constant-oltage Models he circuit above shows the difference between the ideal and constant-voltage model; the two models yield two different break points of slope. Ch3-7

8 3.4 Large/Small-Signal Operation Large-Signal Analysis OU=2.4, Ix=6mA ad=3+0.1ac I x Small-Signal Analysis vout=0.1*(3*rd)/(100+3*rd)=11m, rd=/ix=4.2ohm Ch3-8

9 Small-Signal Analysis in etail d v S v S v S v I e e I e I e I i d d + = = = + ) / (1 / / ) / ( / s I I d di I exp 1 1 = Δ Δ = d d d d S I r r v I = + =, ) ( d r I 1 exp 1 = = = d If two points on the I curve of a diode are close enough the If two points on the I curve of a diode are close enough, the trajectory connecting the first to the second point is like a line, with the slope being the proportionality factor between change in voltage and change in current. Ch3-9 in voltage and change in current.

10 Small-Signal Incremental Resistance r = d I Since there s a linear relationship between the small signal current and voltage of a diode, the diode can be viewed as a linear resistor when only small changes are of interest. Ch3-10

11 3.5 Applications of iode Half-Wave Rectifiers Full-Wave Rectifiers oltage Regulation Limiting Circuits/Clamping Circuits oltage oublers Level Shifters/Switches Ch3-11

12 Half-Wave Rectifier Averycommonapplicationofdiodesishalfwave of is half-wave rectification, where either the positive or negative half of the input is blocked. But, how do we generate a constant output? Ch3-12

13 iode-capacitor With Load Resistor A path is available for capacitor to discharge. herefore, out will not be constant and a ripple exists. Ch3-13

14 Full-Wave Rectifier: Bridge Rectifier he figure above shows a full-wave rectifier, where 1 and 2 pass/invert the negative half cycle of input and 3 and 4 pass the positive half cycle. Ch3-14

15 Complete Full-Wave Rectifier Since C 1 only gets ½ of period to discharge, ripple voltage is decreased by a factor of 2. Also (b) shows that each diode is subjected to approximately one p reverse bias drop (versus 2 p in half-wave rectifier). Ch3-15

16 oltage Regulator he ripple created by the rectifier can be unacceptable to sensitive load; therefore, a regulator is required to obtain a very stable output. t hree diodes operate as a primitive regulator. Ch3-16

17 oltage Regulation With Zener iode out = r r + R 1 in oltage regulation can be accomplished with Zener diode. Since r d is small, large change in the input will not be reflected at the output. Ch3-17

18 Limiting Circuits he motivation of having limiting circuits is to keep the signal below a threshold so it will not saturate the entire circuitry. When a receiver is close to a base station, signals are large and limiting circuits may be required. Ch3-18

19 General oltage Limiting Circuit wo batteries in series with the antiparalle diodes control the limiting voltages. Ch3-19

20 oltage oubler he output increases by p, p/2, p/4, etc in each input cycle, eventually settling to 2 p. Ch3-20

21 oltage Shifter Ch3-21

22 iode as Electronic Switch iode as a switch finds application in logic circuits and data converters. Ch3-22

Microsoft PowerPoint - ch07ysk2012.ppt [호환 모드]

Microsoft PowerPoint - ch07ysk2012.ppt [호환 모드] 전자회로 Ch7 CMOS Aplifiers 김영석 충북대학교전자정보대학 202.3. Eail: kiys@cbu.ac.kr k Ch7- 7. General Considerations 7.2 Coon-Source Stae Ch7 CMOS Aplifiers 7.3 Coon-Gate Stae 7.4 Source Follower 7.5 Suary and Additional