USN

Time: 3 hrs.

2a.b.

c.

4a.

b.

10EC63

for short(10 Marks)

(10 Marks)

Sixth Semester B.E. Degree Examinationo Dec.2013 lJan.2Dl4Microelectronics Gircuits

Max. Marks:100

Note: '' ii',:;:,F:;i{f::#?!r*;'fl|i"lf,,, '

2. State all assumptions, including missing duta.,

b.

c.

3a:

', b.

d()(J

!o

oEoL

6e:no0'cc,o

.=N

iUg6)og:FO

Ez

a=

oo)

boi

>cl

OE

=Eo ..1

o=atE

!oJEo.r>'!bo"trooo==6gotr>Xoo-

rJ<- c'l

oo'7

!o

PART _ ADerive an expression for drain-to-source current ips from in v/s Vos relationship for triodeand saturationregions of n-MOSFET. (10 Marks)For an 0.8pm technology for which tox : 15nm, Fn

: 550 cmzA/. Find k'" and caa and theoverdrive voltage Vo, : Vr, - V1 required to operate a transistor having W/L : 20 insaturation with Ir : 0.2 mA. What is the minimum Vos needed? (06 Marks)Design the circuit shown in Fig.Q.i(c) to obtain a drain voltage of 0.iV. What is theeffective resistance between drain and source? At this operating point, let V1 : 0.8V and

KlfY)= lrnA/v2.'(L/ (04 Marks)

A ^

v00-- 3v

l7oLrrf'vD"'o'lv'a

9

Fig.Q.l (c)

'., .:.

Briefly exp!4in any two types of biasing methods in MOS amplifier circuits. (06 Marks)For a eommon source amplifier with g. : 2 mNY, r0 : 50Kf) and Rp : 10Kf),Rc

= 10MO, RL :20KO and Rrlr: 0.5Mf). Calculate Rin, Gu, Au, A,o. R.ut. (10 Marks)

Menfion any 4 comparison of important characteristics of MOSFET and the BJT. (04 Marks)

Explain the CMOS implementation of IC common source amplifier and hence eXplain howto determine its small signal voltage gain.

" (t0 Marks)

For the common gate amplifier with WL: 41tntl0.2pm. prnCox:350 VNY2, r0: 18 Kf),Ip : 100prA, g.: 1.2 mAlY, X:0.2, R,: 10Kf), Ri_ : 100 KQ, Cg,:20fF, C*6 = 5ff,Cr-:5ff. Find Aro, Rin, Rout, Gu, Gir, Gi and fu. (10 Marks)

Explain the circuit of MOS cascade amplifier andcircuit transconductance Gy.Explain briefly with neat circuit diagrams:i) Wilson MOS mirrorii) Widlar current source.

hence obtain an expression

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PART _ BExplain the basic operation of BJT differential pair.

10EC63

(08 Marks)

(06 Marks)(06 Marks)

',"

performance of logic(08 Marks)(05 Marks)

using equivalence or(07 Marks)

iir

5a.b.

6a.b.

For the nMOS differential pair with a common-mode voltage V.* applied as shown inFig.Q.5(b). let Voo : Vss : 2.5Y, K: W/L =3mAlY2, Vtn : O.7Y,I : 0.2mA, Ro : 5Kf).Neglect channel length modulation.i) Find Vov and V6s for each transistor.ii) For Vcrr,r: 0 find V., ior, ioz, Vor and Voz.iii) Repeat (ii) for V..: lV.ir) What is the highest value of V., for which Qr and Q2 remain in saturation, if currentsource I requires a minimum voltage of 0.3V to operate properly. What is the lp-west value

(12 Marks)

Explain briefly with expressions the properties of negative feedback. (08 Marks)

,fu1V, and hence for V.-.

.,i' I

A series-shunt feedback amplifiei employs a basic amplifier with input and outputresistances each of 1KQ and gain A : 2000 VA/. The feedback factor B

: 0.1 V/V. Find thegain Althe input resistance Rjr and output resistance R", of the closed loop amplifier.

Explain briefly u, urtq;i;u. uro.ou.h for finding roo#guin aB.

Explain instrum€ntation amplifier with neat circuit diagrams. ' (08 Marks)With neat diaEam, explain the sample and hold circuit using opamp. (07 Marks)Derive an. expression for an input resistance of the inverting amplifier taking into accountthe finite'open loop gain A of the opamp shown in Fig.Q.7(c). (05 Marks)

c.

7a.b.

c.

Fig.Q.7(c)

a. Briefly discuss the parameters used to characterize the operation andcircuit families.

b. Write the expressions for propagation delay of an inverter.c. Sketch a CMOS logic circuit that realizes the function Y = ag + AB

co-incidence function.

",.;, F,igQ.5(b).

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