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(ELEC202)f72af6 - exam1_MT.pdf
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ELEC 202 Midterm Examination Oct. 20, 2005

Name: ID No.
Chinese Name:
1 4
2 4
3 14
4 18
Total 40

The following equations may be useful: W
kn' = nCox kn = nCox
L For Vds < Vgs C Vtn Id = nCox W [(Vgs C Vtn)Vds C 1 Vds2]
L2 For Vds > Vgs C Vtn Id = 1 nCox W (Vgs C Vtn) 2(1 + nVds)
2L
. b b2 . 4ac
For ax2 + bx + c = 0 x1,2 = 2a
(1) For the following diode circuit with ideal diodes (Vd = 0), 4 marks sketch accurately the voltage transfer characteristics (VTC,Vo vs Vi) for Vi from 0V to 5V.

ELEC 202 Midterm Examination Oct. 20, 2005

(2) For the following circuit, find Vo and Id. 4 marks Given Vtn = 0.7V, kn = 80A/V2, n = 0, Vtp = C0.7V, kp = 20A/V2, p = 0.

ELEC 202 Midterm Examination Oct. 20, 2005

(3a) A single-stage inverting amplifier is shown below. Using the graph 8 marks paper provided, sketch the IV characteristics (Id vs Vds) of the transistor M1, and the load lines for R1 = 25k. and R1 = 50k.. Given Vtn = 0.8V, kn = 500A/V2, n = 0. You may not need to compute points in the triode regions.
5V
R1

Vo
Id
Vi

ELEC 202 Midterm Examination Oct. 20, 2005

(3b) From the IV curves and the load lines of (3a), sketch the voltage transfer 4 marks characteristics (Vo vs Vi) for the two cases.

(3c) From either the IV curves or the VTC curves, determines the gains of 2 marks the amplifier with R1 = 25k. and R1 = 50k..
ELEC 202 Midterm Examination Oct. 20, 2005

(4a) Determine the DC voltages of Vo1 and Vo2 for the following circuit 4 marks with Vi = 1V. Given that Vtn = 0.8V, kn = 5mA/V2, n = 0.1/V, Vtp = C0.8V, kp = 5mA/V2, p = 0.1/V. For calculating the DC voltages, you may ignore channel length modulation.
5V
35k.
25k. Vo2


M2
Vo1

M1Vi

(4b) Draw the small signal model of the circuit in (4a) including the output 8 marks resistances of M1 and M2, and derive the gain of A1 = vo1/vi and the gain of A2 = vo2/vo1.
ELEC 202 Midterm Examination Oct. 20, 2005

(4c) Now, Vi changes from 0.95V to 1.05V sinusoidally. With the knowledge 4 marks
of (4b), sketch the waveforms at Vo1 and Vo2.
(4d) Compute the output resistance of the circuit in (4a). 2 marks