EE 438
Homework #20
The two BJT’s in the differential amplifier circuit in Fig. 1 are identical. Their parameters are
I
S
= 10
-15
A,
β
= 100
,
V
A
→
∞
.
The parameters for the MOSFETs in the differential amplifier circuit in Fig. 2 are
NMOS:
k
n
’
= 20
µ
A/V
2
,
W
= 200
µ
m,
L
= 10
µ
m,
V
tn
= 1 V,
λ
= 0.04 V
-1
PMOS:
k
p
’
= 10
µ
A/V
2
,
W
= 100
µ
m,
L
= 10
µ
m,
V
tp
= -1 V,
λ
= 0.04 V
-1
1.
In the differential amplifier circuit of Fig. 1 let
I
= 1 mA,
R
C
= 5k
Ω
,
R
E
= 200
Ω
,
and
V
CC
=
V
EE
= 5 V.
Perform a DC analysis using the expression
(use
V
T
BE
V
V
S
C
e
I
I
/
=
T
= 25.88 mV) to find the
voltages
(a)
V
E1
,
(b)
V
X
, and
(c)
V
C1
. Also, determine
(d)
g
m
, and
(e)
r
e
.
2.
Use a small signal equivalent of the circuit in Problem 1 with the values of
g
m
and
r
e
determined in that problem to find
(a)
the differential voltage gain,
2
1
2
1
i
i
c
c
v
v
v
A
−
=
v
v
−
, and
(b)
the
differential input resistance,
R
id
.
3.
In the MOSFET differential amplifier circuit of Fig. 2 let

This
** preview**
has intentionally

**sections.**

*blurred***to view the full version.**

*Sign up*