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(ELEC202)pass_mt2.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 2002 Room 2440
MID-TERM #2

(12 November 2002 4:50 pm - 5:50 pm)
Name: ________________________ Chinese Name: ______________________
Student No.: ________________________ Signature: ______________________
*Individual marks for each section are shown in [ ] brackets. Total = 40 marks.
(1) The MOS amplifier shown below are biased with a current source formed by M1, M2 and M3. The size of each transistor is labelled in the figure. Assume nCox = 100 A/V2, Vtn = 1 V and n = 0.01 V-1 for the NMOS; and
pCox = 50 A/V2, Vtp = .1 V and p = 0.02 V-1 for the PMOS.
(a)
Find the DC biasing current ID of each transistor. [8]

(b)
Find the output resistance Ro and the small signal voltage gain vo/vi of the amplifier. [12]


VDD = 5 V

W 10
..
----
= ---------
..
L1 2
vo
RBias
500 .

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(2) Assume all BJTs in the current source shown below are matched with = 100, VA = 100 V, VBEon = 0.7 V, VCEsat = 0.2 V, VT = 25.9 mV and IS = 1.810.15 A.
(a)
Find the value of resistor Rref such that the reference current Iref = 1 mA. [2]

(b)
Find the output current IO. Keep your answer corrected to 3 significant digits. [7]

(c)
Find the output resistance of the current source. [9]

(d)
Find the minimum output voltage VOmin of the current source. [2]


VCC = 10 V

RO Iref


+

IO
VOmin 10 k.
_


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