ECE65 (Winter 2007), Midterm
Name:
Notes: 1. Write your answers on these three sheets.
2. For each problem, 20% of points are alloacted for the correct final answer.
3. Use the following information in solving or designing circuits: OpAmps are powered
by ±15 V power supplies (power supplies not shown), have a unity-gain bandwidth of
106Hz, a short-circuit current limit (maximum output current limit) of 250 mA, and a
slew rate of 1 V/µs. In circuit design, use commercial resistor and capacitor values of 1,
1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.7, 3., 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5,
8.2, 9.1 (×10nwhere nis an integer). You can also use 5 mH inductors.
Problem 1. Design a circuit with a transfer function of H(j ω) = 1
1−j105/ω and a
minimum input impedance of 10 kΩ. (10pts)
The transfer function is for a first-order high-pass filter with ωc= 105rad/s. Since
K= 1, we can (and should) use a passive filter. Prototype of the circuit is shown below
with
vo
i
v
C
R
+
−
+
−
ωc=1
RC = 105
Zi|min =R≥10 kΩ
Choosing R = 10 kΩ, we get:
C=1
Rωc
=1
104×105= 10−9F = 1 nF
Therefore, R= 10 kΩ and C= 1 nF (both commercial values).
