Problem 5. Find vo /vi . (Assume OpAmp is ideal).
Problem 6. The circuit below is a voltage-to-current converter with IL = gVi. Find the
value of g and show that it is independent of RL . (Assume OpAmp is ideal).
vi
+
v
o
+
−
R1
−
IL
R1
−
R2
R1
−
R2
R1
+
vi
R3
+
RL
R2
R2
Problem 5
Problem 6
Problem 7. Assume the OpAmp in the circuit below is ideal. Find the voltage transfer
function H(jω) = Vo /Vi .
Problem 8. Find vo in terms of v1 and v2 . (Assume OpAmp is ideal).
Vi
2R
R
Vo
−
C
+
V1
R
R2
Problem 7
R
−
+
R1
4R
−
V2
2R
Vo
+
Problem 8
Problem 9. Consider the amplifier circuit below with vi = 0.5 cos(ωt). a) what is the
amplifier gain in dB? b) For what range of frequencies, does this amplifier behave as a linear
amplifier? (Assume a unity-gain bandwith of 106 Hz, ISC = 100 mA, S0 = 1 V/µs and
OpAmps are powered by ±15 V power supplies.)
Problem 10. Consider the inverting amplifier below with RL = 500 Ω. The input signal
is vi = 1 cos(106 t) V. We want the amplifier to behave linearly (i.e., output signal to be
sinusoidal) and Vo /Vi = −K. What is the maximum value of K we can choose? (Assume
a unity-gain bandwith of 107 Hz, ISC = 10 mA, S0 = 4 V/µs and OpAmps are powered by
±15 V power supplies.)
ECE65 Lecture Notes (F. Najmabadi), Winter 2008
66