Specifications - Microelectronic Devices and Circuits - Solved Exam, Exams of Microelectronic Circuits

Download Specifications - Microelectronic Devices and Circuits - Solved Exam and more Exams Microelectronic Circuits in PDF only on Docsity! Problem1 (15 pts., NO Partial Credit) You buy three voltage amplifiers with the following specifications: Rj, = 10°, Ry, = 105,A = 10. You hook them up in series (i.e., output 1 = input 2, etc.), and place them in a black box. You are going to sell this box as a transconductance amplifier. What are the specifications of the transconductance amplifier? A A A Mou? hy ALA, x K Ro 1 2 3 we ay Restle transconductance amplifier 3 G ol SKID & R, = o> Je Problem 2 (15 points) a. Find the phasor representing the ratio of short-circuit output current to input current for the following circuit: ot §: wh ge te lor = - 4. 2 mG, Cae, x sc R, Ju, P Re. BF it wad, Alay in b. What is the general shape of the frequency response? Sketch magnitude vs frequency on dB scale provided on pg. 2. SINGLE POLE LOW - PASS 1ofé  } Rot Reoy os | ~~ 1 + + lyn “4 ) Ay Ys ne Ra Oils oer he \{ 7 7 2 At a it ee Voor = Gy Rear Vv Cush Ag Rin Re 1 —~— ro: Me Reap Roy Rog 3 ‘° + io°* dB A qok to (492) 20d oe a L 4 — he, logw 2o0f8 Problem 4 (25 points) In the circuit below, the reference node A is at a potential of 1.5 V. The W/L ratios for the n-channel devices are chosen as: (W/L), = 2(W/L), . For the p-channel devices (W/L), = 10(W/L),. Also, (F) = 4(¥) . 3 1 a. Find W/L for n-channel device MNi (to produce the required 1.5 V at node A). b. Find the drain current of MN2 and the node voltage Vy. c. Find the value of R, needed to produce a voltage of 3 V at node Z. Vpp = 6V oo => a > SV. Up2 us PI o,2 eosmuh (W/L), = Q& uu Oaks Cx ML Vos Ye)” Sus . z Ne Le aX SO O | > Ww pa 1, vL\ >a “ ?P 100k ” u juoyh= A Cal, Y | Voe-Yr) AsV 3 Vv = fn Vy olledgiy te Toy = Tha VIO = tow R,= OK Sots Pr Probtem 5 (25 points) a) You are given one “power nMOS” transistor and need to construct a transistor circuit to drive an 8 ohm speaker through a coupling capacitor Cy. (The “power nMOS” transistor has a 1V threshold, a W/L of 104, and pC, = SOMA/V 2. The source is connected to the body internally.) Your circuit should have a voltage gain of about 0.5 at higher frequencies (that is, at frequencies high enough that the impedance of Cy is negli- gible). (Note that Cy must be quite large to have a good low frequency response.) The bias current source you have available is essentially ideal (i.e., infinite parallel resistance). You choose the circuit below. Rs Vop C 100KQ ce = vel Ins GQ speaker a) Draw the small-signal mode! for this amplifier in the box opposite, ignoring all internal device capacitances and parasitic resistances. BE niea YNeuce SS MMe O© ON foreccr AMP Hooee OL b) Solve for the “mid-band” gain A,, (formula in terms of circuit and device parameters). The mid-band gain is areal quantity. It is the gain at frequencies high enough that coupling capacitors act as shorts, yet the fre- quency is low enough that capacitors to ground are negligible. fou SSHOMRL — Unyr? Gn(Ug-V2) Voll QL itm olf gr toll Ay = c) Find the mid-band gain of the circuit Ay, at a bias current of Ip,as = 10 mA. @lomk w= Yr - av Use Vp = O.2V =ab ~— fe bycVe Ot 4 vo {lite = RL 4, = O44 Tos  . (pz | | % i & . Vas o ay Small-signal Model ee ok b. pF Brn, Vv We ate £ Us © Tyr J ™~ a Con # (Vsa-Uy) > MoV, = O,2_ 8of8