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(ELEC202)ee202_03_pass_mt1.pdf
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THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING

Elec 202 Philip Mok
ELECTRONIC CIRCUITS II

Fall 2003 Room 2440
MID-TERM #1
(14 October 2003 10:35 pm - 11:45 pm)
Name: ________________________ Chinese Name: ______________________ Student No.: ________________________ Signature: ______________________ *Individual marks for each section are shown in [ ] brackets. Total = 40 marks.
(1) Assume the transistor below is operating in saturation region with = 100, |VBEon| = 0.7 V and |VCEsat| = 0.2 V.
(a)
Find the value of resistor RE such that VC = 0.6 V. [6]

(b)
What are the forced and overdrive factor of the transistor? [4]


V
CC = 5 V RC 5 k.
VE
RB
VB


1 k.
VC
RE
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(2)
For the amplifier shown below, all the transistors operate in active region with |VBEon| = 0.7 V, VT = 26 mV, = 20 and |VA| = 20 V.

(a)
Assume = in the calculation, find the DC collector current IC1 and IC2 of Q1 and Q2, respectively. [2]

(b)
Use the values in part (a) to calculate the AC small signal parameters gm, r, re and ro of Q1 and Q2. Use = 20 in the calculation. [2]

(c)
Find the input resistance Ri, output resistance Ro, and voltage gain vo/vi of the amplifier.


[11]

(3)
For the amplifier circuit shown below, assume |VBEon| = 0.7 V, = 20 and VA = .

(a)
Find the collector currents IC and the DC voltage at nodes X. Do NOT assume = in the calculation. [5]

(b)
Find the input resistance Ri, output resistance Ro, voltage gain vo/vi and current gain io/ii of the amplifier. [10]





VCC = 5 V
+
vi
_

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