Download ETEE3212 Spring 2008 Test

ETEE3212
Spring 2008
Test #2
Name:________________________
Show all work. Clearly indicate final answer(s).
CHEATSHEET(S) MUST BE TURNED IN WITH TEST OR A ZERO WILL BE
RECEIVED FOR ENTIRE TEST!
1. (40 points) Determine the low-frequency
response for the ER amplifier to the right when
CC=4µF, CB=2µF, R1=10kΩ, R2=90kΩ,
RC=1kΩ, RE=200Ω, RL=2kΩ, β=100,
VBE=0.7V, VCC=20V, and RS << Rin.
Extra Credit (20 points max): Sketch the straight
line approximations for the gain and phase Bode
plots and provide values for actual plots.
2. (30 points) Consider an inverting amplifier with an ideal gain of 1000 V/V constructed from
an op amp with an input offset voltage of 3 mV and with output saturation levels of + 10V.
Hint: Assume RF >> Ro and that Go, Rcm and Ri are much larger than either RA or RF.
a. What is (approximately) the peak sine-wave input signal that can be applied without
the output clipping?
b. If the effect of Vio is nulled at room temperature (25oC) how large an input may be
applied if:
i. the circuit is to operate at a constant temperature of 25oC?
ii. the circuit is to operate at a temperature in the range 0oC to 75oC and the
temperature coefficient of Vio is 10µV/oC?
3. (30 points) Design a single 741 op-amp that will generate vout = 3v1 + 5v2 – 8v3 - 6v4, when
the equivalent resistance at the negative and positive terminals is Req=8kΩ. Determine each
resistor value, input resistance at each of the amplifier inputs and the output resistance. Draw
the schematic and show the resistor values.
Extra Credit (Maximum 15 points) Design an emitter-resistor circuit as shown in Problem 1 with
VCC=12V, β=250, RL=1kΩ, RS=2kΩ and AV = -5 V/V. Select CB and CC so that the amplifier
has a lower 3dB frequency of 20Hz. IC is to be in the middle of the ac load line.
P1
P2
P3
EC