Title: Differential Amplifiers
1Differential Amplifiers
2Differential Transistor Pairs
MOSFET Diff-Pair
BJT Diff-Pair
3Differential Transistor Pairs
MOSFET Diff-Pair
BJT Diff-Pair
The bottom transistor (the one with Ibias) sets
the total current
4Differential Transistor Pairs
MOSFET Diff-Pair
BJT Diff-Pair
The bottom transistor (the one with Ibias) sets
the total current
The upper two transistors compete for a fraction
of this current
5Analysis of Diff-Pair
6Analysis of Diff-Pair
7Analysis of Diff-Pair
8Analysis of Diff-Pair
9Analysis of Diff-Pair
10Analysis of Diff-Pair
Source of Common-Mode Gain
11Analysis of Diff-Pair
12Analysis of Diff-Pair
13Differential Pair Currents
3
Iout
Iout-
2.5
2
(nA)
1.5
Output current
1
0.5
0
-0.
4
-0.
3
-0.
2
-0.
1
0
0.1
0.2
0.3
0.4
Differential input
voltage (V)
14Transistor Leg Currents
15Transistor Leg Currents
16BJT Differential Pair Analysis
-
Iout
Iout
V1
V2
Vb
GND
17BJT Differential Amplifier
-
Iout
Iout
V1
V2
Vb
GND
18BJT Differential Amplifier
V1
V2
Vb
GND
19BJT Differential Amplifier
Fixed output voltage Current output
Zero output current Voltage output
V1
V2
Vb
GND
20Basic Differential Amplifier
21Transfer Functions
22Wide-Output Range Differential Amplifier
Simple differential amplifer
"Vmin" effect
23Wide-Output Range Differential Amplifier
Wide-output range amplifier
24Wide-Output Range Differential Amplifier
Wide-output range amplifier
25A Unity-Gain Follower
26A Unity-Gain Follower
27A Unity-Gain Follower
Amp Gain Av
Av
Solving Vout Vin
1 Av
A more ideal Follower / Buffer Circuit
28A Unity-Gain Follower
Amp Gain Av
Solving Vout Vin
29A Unity-Gain Follower
Amp Gain Av
Solving Vout Vin
30Differential Pairs / Amplifiers
- Differential Transistor Pairs
- Differential Amplifiers
- Unity-Gain Amplifiers