Name: ID#:
ECE 340
Online Midterm Exam (1 hour 30 minutes) February 25, 2021 (Winter 2021)
Answer all questions in the space provided (Open book exam) Make reasonable assumptions as necessary. Calculators are allowed.
30 minutes extra provided for online submission to the Learn dropbox. Exams submitted after the 2 hour mark penalized at the rate of 1 mark per minute late.
NAME: ID #:
Q1
/20
Q2
/20
Q3
/20
Total Mark:
/60
ECE 340 Midterm Exam (1 hour 30 minutes) Page
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Name: ID#:
1. Active Load Amplifier (20 marks)
For the circuit below, calculate the small signal Rin, Rout and gain Vout/Vin. (5 marks each for total of 15 marks) Do not neglect ro. Identify at least two benefits the active load can provide? Based on the expressions derived for Rin and Rout, discuss at least three benefits/disadvantages that may arise from using the active load for the circuit shown below. (5 marks)
Q3
Ibias
Q2
Vout Vbias
Rout
Q1
Rin Vin
ECE 340 Midterm Exam (1 hour 30 minutes)
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Name: ID#:
2. Two-stage amplifiers and frequency response (20 marks)
+5 V
10 k
Q1
R1
0.5 mA
0.5 mA
For the circuit shown above, let = 100, C = 2 pF, fT = 400 MHz. (a) Calculate the mid-band gain.
vi + −
+20 V
R2
10 k vo
Q2
ECE 340 Midterm Exam (1 hour 30 minutes)
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(10 marks)
Name: ID#:
(b) Calculate the upper 3-dB frequency. (10 marks)
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Name: ID#:
3. Two-stage BiCMOS amplifier (20 marks)
A BiCMOS Darlington is shown in the figure below. The bias voltage VB is adjusted for a dc output of 2 V. Calculate the bias currents in both devices (5 marks each for a total of 10 marks) and then calculate the small signal voltage gain vo/vi of the circuit. (10 marks)
For the MOS transistor, assume W = 10 m, L = 1 m, nCOX = 200 A/V2, Vt = 0.6 V, = 0.25 V1/2, f = 0.3V and = 0.
For the BJT, assume IS = 10-16 A, F = 100, rb = 0, and VA→. VCC = 3 V
RL = 1 k
M1
RB = 1 k
+
vo
−
+
− vi
VB
Q2
ECE 340 Midterm Exam (1 hour 30 minutes)
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Name: ID#:
ECE 340 Midterm Exam (1 hour 30 minutes)
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