Microelectric Circuits 14

Please check my work and if incorrect give me the correct answer Please refer to the problem stated in the attached file. (For the amplifier shown below, let Vdd = 5 V, Rd = 12 k ohms, Vt =1 V, k'n = 25 µa/V2, W/L = 20, Vgs = 2 V and lambda = 0. Find the dc current Id and the dc voltage Vd. ) My solution: Id=(k'n*Vt*W/L)/Vgs=25*1*20/2=250microA Vd=12K*.250=3V Answer is C

Microelectric Circuits 15

Please check my work and if incorrect give me the correct answer Please refer to the problem stated in the attached file. (For the circuit shown below, find Vs and Id. The MOSFET has k'n(W/L) = 0.5 mA/V2 and Vt = 3 V. Assume lambda = 0.) Solution: The only way I could solve this problem was by trial and error using possible values of Id Taking: Id=.9 k'n(W/L) = 0.5 mA/V2 Vov=sqrt(2*Id/muCox(W/L))=Sqrt(2*.9/.5)=Sqrt3.6=1.897 -(Vov+Vt)=-(1.897+3)=-4.9V Answer is B

Microelectric Circuits 17

Please check my work and if incorrect give me the correct answer Please refer to the problem stated in the attached file. (For the differential amplifier shown below, beta = 80. Evaluate the overall voltage gain vo/vs (neglect the effect of ro).) My solution: Rei=re2=Vt/Ie=25mV/.5mA=50 Ohm Rid=2(Beta+1)*(Re+Re) =2*81*(50+150)=32400=32.4 KOhms Vid/Vsig=Rid/(Rsig+Rid)=32.4/(10+32.4)=.764 Voltage gain from loose to the output is Vo/Vid=(total resistance in the collectors)/(total resistance in the emittor) =2Rc/(e(re+RE)=(2*10)/(2*(50+150)*10^-3)=50V/V The overall differential voltage gain can now be found as Ad=Vo/Vsig=Vd/Vsig*Vo/Vid=.764*50=38.2 Answer is C

Microelectric Circuits 18

Please check my work and if incorrect give me the correct answer Please refer to the problem stated in the attached file. (For the circuit shown below, Vcc = 6 V. Assume that Vbe is approximately 0.7 V and neglect the effects of ro and the finite beta. Find the value of R that results in Io = 1 mA.) My answer is: Vcc=6V Vb=.7 Io=1Ma VEE=1 I=Iref=(Vcc+Vee+Vbe)/R Solve for R 1 mA=(6V+.7-1)/R R=5.7/1=5.7 C is the answer

Microelectric Circuits 19

Please check my work and if incorrect give me the correct answer An MOS differential amplifier utilizes a bias current of I = 20 µA. The devices have Vt = 1V, W = 120 µm, L = 6µm, and µnCox for this technology is 25 µA/V2. Find gm. a. 0.04 mA/V b. 0.05 mA/V c. 0.06 mA/V d. 0.07 mA/V My answer is: I=20 microA Vt=1V W=120microM L=6microM Mu-nCox=25microA/V2 find gm= gm= sqrt(2*Mu-nCox*W/L*Ic) =sqrt(2*25*120/6*20microA) =sqrt20=4.47 Answer is A