ECE 137 A Mid-Term Exam: Circuit Analysis and Transistor Biasing, Study notes of Mathematics

Download ECE 137 A Mid-Term Exam: Circuit Analysis and Transistor Biasing and more Study notes Mathematics in PDF only on Docsity! ECE 137 A Mid-Term Exam February 7, 2005 Do not open exam until instructed to. Closed book: Crib sheet and 1 page personal notes permitted There are 2 problems on this exam, and your have 50 minutes. Use any and all reasonable approximations (5% accuracy is fine. ) , AFTER STATING and approximately Justifying them. Name: _______________________ Problem Points Received Points Possible 1a 5 1b 5 1c 5 1d 15 1e 15 1f 5 1g 20 2a 12 2b 13 2c 5 total 100 1 a Problem 1, 70 points You will be working on the circuit below: Vgen Rgen Rg1 RSS1 Rc2 RL Reac2 Ree2 CE Cout VoutVin Q1 Q2 -Vdd -Vdd +Vss +Vss Q1 : thV =1 Volts. = 2 mA/V, goxsat WCv 0=λ (P-channel enhancment mode device) Q2: β =200, =75 V +Vss=+10 volts. -Vdd= -10 volts Rgen=1 MOhm RL=500 Ohm AV Rg1=2 MOhm Reac2=50 Ohm Rss1= ??? Ree2= ??? Rc2= ??? EC and Cout are very big and have negligible AC impedance. 2 a Part c, 5 points Find the small signal parameters of Q1 and Q2. Transistor Q1: gm=_________ Rds=________ Transistor Q2: gm=_________ Rce=____________ Rbe=_________ 5 a Part d, 15 points. Find the small signal voltage gain (Vc2/Vb2) of Q2 and Q2's small-signal input resistance. Vc2/Vb2=____________________________ Rin,q2= ____________________________ 6 a Part d, 15 points Find the small signal voltage gain (Vs1/Vg1) of Q1 and the *** amplifier *** input resistance. Vs1/Vg1= _________________________ Rin,amplifier =__________________________ 7 a 10 a Problem 2, 30 points nodal analysis Vout Vin Q1 Q2 You will be working on the circuit to the left. Ignore DC bias analysis. You don’t need it. The two transistors have transconductance gm1 and gm2 respectively. Their output resistances Rds1 and Rds2 are both infinity. Part a, 12 points Draw a small-signal equivalent circuit of the circuit 11 a Part b,13 points Find, by nodal analysis, a small-signal expression for Vout/Vin. Vout/Vin= __________________ 12 a