EE PRO for TI - 89, 92 Plus
Equations - Linear Amplifiers
102
Chapter 28
Linear Amplifiers
This section covers linear circuit models (i.e., small signal models) used in making first order calculations using
bipolar or junction transistors in amplifier circuits. These circuit models are referred to by many different names
such as small signal circuit model, AC circuit model, linear circuit model. In addition, popular device
configurations such as the Darlington pair, emitter-coupled pair, differential amplifier, and a source-coupled pair
topics have been included.
BJT (Common Base)
BJT (Common Emitter)
BJT (Common Collector)
FET (Common Gate)
FET (Common Source)
FET (Common Drain)
Darlington (CC-CC)
Darlington (CC-CE)
Emitter-Coupled Amplifier
Differential Amplifier
Source-Coupled JFET Pair
Variables
The table lists all variables used in this section along with a description and appropriate units.
Variable
Description
Unit
α
0
Current gain, CE
unitless
Ac
Common mode gain
unitless
Ad
Differential mode gain
unitless
Ai
Current gain, CB
unitless
Aov
Overall voltage gain
unitless
Av
Voltage gain, CC/CD
unitless
β
0
Current gain, CB
unitless
CMRR
Common mode reject ratio
unitless
gm
Transconductance
S
µ
Amplification factor
unitless
rb
Base resistance
Ω
rrc
Collector resistance
Ω
rd
Drain resistance
Ω
re
Emitter resistance
Ω
RBA
External base resistance
Ω
RCA
External collector resistance
Ω
RDA
External drain resistance
Ω
REA
External emitter resistance
Ω
RG
External gate resistance
Ω
Ric
Common mode input resistance
Ω
Rid
Differential input resistance
Ω