1064
∗∗
∗∗
∗∗
Chapter 14 Single-Transistor Amplifiers
14.99. The common-base amplifier in Fig. 14.83 is the implementation of the design from Design Ex. 14.11
using the nearest 1 percent resistor values. (a) What
are the worst-case values of gain and input resistance if the power supplies have ±2 percent tolerances? (b) Use a computer program or spreadsheet
to perform a 1000-case Monte Carlo analysis to
find the mean and 3σ limits on the gain and input
resistances. Compare these values to the worstcase estimates from part (a).
14.100. Use PSPICE to perform a 1000-case Monte Carlo
analysis of the circuit in Fig. 14.83 assuming the
resistors have 1 percent tolerances and the power
supplies have ±2 percent tolerances. Find the
mean and 3σ limits on the gain and input resistance at a frequency of 10 kHz. Assume that the
current gain β F and V A are uniformly distributed
in the intervals (60, 100) and (50, 70), respectively.
Use C1 = 100 F, C2 = 1 F, and f = 10 kHz.
14.101. Suppose that we forgot about the factor of 2 loss
in signal that occurs at the input of the commonbase stage in Ex. 14.11 and selected VCC = VE E =
2.5 V. Repeat the design to see if the specifications
can be met using these power supply values.
14.102. (a) Use a spreadsheet or other computer tool to
perform a Monte Carlo analysis of the design in
Fig. 14.34. The resistors and power supplies have
5 percent tolerances. VT N is uniformly distributed
in the interval [1 V, 2 V], and K n is uniformly
distributed in the interval [10 mA/V2 , 30 mA/V2 ].
(b) Use the Monte Carlo option in PSPICE to perform the same analysis at a frequency of 10 kHz
for C1 = 4.7 F and C2 = 68 F. Compare the
results.
RI
ii
io
Rin
vi
RG
Rout
RL
vo
Figure 14.84
14.104. (a) What are the values of Av , Rin , Rout , and
Ai for the common-source stage in Fig. 14.85 if
R I = 75 k, RG = 1 M, R L = 2 k, and
R S = 200 ? Assume gm = 10 mS, ro = 10 k,
and η = 0.75. (Ai = i o /i i ).
RI
io
ii
Rout
Rin
vi
RG
RL
vo
RS
Figure 14.85
14.105. (a) What are the values of Av , Rin , Rout , and Ai
for the common-gate stage in Fig. 14.86 operating
gm = 0.5 mS, η = 1, R I = 50 , R S = 100 k
and R L = 100 k? (Ai = i o /i i ).
RI
ii
14.8 The Influence of Body Effect on Amplifier
Performance
14.103. (a) What are the values of Av , Rin , Rout , and
Ai for the common-drain stage in Fig. 14.84 if
R I = 100 k, RG = 1.5 M, R L = 1 k,
gm = 10 mS, and η = 0.5? (Ai = i o /i i ).
vi
io
Rin
RS
Figure 14.86
Rout
RL
vo