ALL ABOUT HOW IT WORKS AND ITS ANALYSIS

1. EE-4232
Differential Amplifiers
0

2. Different modes of operation of the differential pair: The differential pair with a common-
mode input signal vCM.
1

3. Different modes of operation of the differential pair: The differential pair with a “large”
differential input signal.
2

4. Different modes of operation of the differential pair: The differential pair with a large input
signal of polarity opposite to that in (b).
3

5. Different modes of operation of the differential pair: The differential pair with a small
differential input signal vi.
4

6. Transfer characteristics of the BJT differential pair of previous figure assuming α ≅ 1.
5

7. The current and voltages in the differential amplifier when a small
difference signal vd is applied.
6

8. A simple technique for determining the signal currents in a differential amplifier
excited by a differential voltage signal vd; dc quantities are not shown.
7

9. A differential amplifier with emitter existence. Only signal quantities are shown (on color).
8

10. Equivalence of the differential amplifier (a) to the two common-emitter amplifiers in
(b). This equivalence applies only for differential input signals. Either of the two
common-emitter amplifiers in (b) can be used to evaluate the differential gain, input
differential resistance, frequency response, and so on, of the differential amplifier.
9

11. (a) The differential amplifier fed by a common-mode voltage signal. (b) Equivalent
“half-circuits” for the common-mode calculations.
10

12. Analysis of the current mirror taking into account the finite β of the BJTs.
11

13. Generation of a number of cross currents.
12

14. A current mirror with base-current compensation.
13

15. The Wilson current mirror.
14

16. The Widlar current source.
15

17. 16

18. A differential amplifier with an active load.
17

19. Small-signal model of the differential amplifier.
18

20. The MOSFET differential pair.
19

21. Normalized plots of the currents in a MOSFET differential pair. Note that VGS is the
gate-to-source voltage when the drain current is equal to the dc bias current (I/2).
20

22. MOS current mirrors: basic
21

23. MOS current mirrors: cascode
22

24. MOS current mirrors: Wilson
23

25. MOS current mirrors: modified Wilson
24

26. A multistage amplifier circuit.
25

27. References
• Electronics by A. Hambley
• Microelectronics Circuits by Sedra & Smith
• Other books on Electronics
26