EE 140 ANA ALOG INTE EGRATED CIRCUITS S SPRING 2011 C Ngguyen PROBL LEM SET T 2 Issued Tu uesday Feb 1 1 2011 Due Tuessday Feb 8 2011 2 5 00 p m m in the EE 140 homeworrk box in 2400 Cory 1 Use U inspectio on analysis to t write exprressions for the input reesistance Ri output resisstance Ro and gain vo vS for eacch of the am mplifiers in F Fig PS2 1 T The expressiions should be in teerms of the given g elemen nts and param meters of thee small signnal equivalennt circuits i e gm rp r etc for the tran nsistors used d For each ccircuit assuume that all ccapacitors shhown have infinite values v a c b d Fig F PS2 1 2 Find the inpu ut resistance Ri and the vo oltage gain vo vs of the ccircuit in Figg PS2 2 usinng in nspection analysis Expllain the purp pose of the 100 k resisttor EE 140 ANALOG INTEGRATED CIRCUITS SPRING 2011 C Nguyen 0 5 mA vo 8 100 k 1 k 8 Ri Rs 50 vs Fig PS2 2 3 The BJT values of the BJT in the emitter follower of Fig PS2 3 may range from 20 to 200 For each extreme 20 and 200 find a IE VE VB b Ri c vo vs 9 V 100 k 8 10 k 8 Ri vo 1 k 1 k Fig PS2 3 4 For the circuit in Fig PS2 4 let transistor Q1 have 20 and transistor Q2 have 200 and neglect the effect of ro Use VBE 0 7 V EE 140 ANA ALOG INTE EGRATED CIRCUITS S SPRING 2011 C Ngguyen a Find the t DC emittter current of Q1 and Q2 Also find tthe DC voltaages VB1 andd VB2 b If a lo oad resistance RL 1 k is connectedd to the outpput terminal find the volltage gain from f the basee to the emittter of Q2 vo vb2 and finnd the input rresistance lookin ng into the base of Q2 Rib2 c Replaacing Q2 with h its input reesistance Rib22 found in bb analyze thhe circuit of emitteer follower Q1 to determine its input resistance Ri and the gaain from its bbase to its emitter e ve1 vvb1 d If the circuit is fed d with a sourrce having a 100 k resiistance findd the transmiission to the base of Q1 vb1 vs e Find the t overall voltage gain vo vs includinng the resisttances addedd in parts b aand d Fig F PS2 4 5 Calculate C the output o resistan nce roc of the circuit in Figg PS2 5 as a ffunction of IBIIAS Do not neeglect ro1 or ro2 in this calcculation but you y may negleect rb and r If IC2 1 mA A what is roc for IBIAS 1 mA For IBIAS 0 B Fig F PS2 5
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