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Unformatted text preview: EECS 105, Midterm #2, Fall 1993 EECS 105, Fall 1993
Midterm #2
Professor R. T. Howe Ground Rules:
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q Closed book and notes; one formula sheet (both sides)
Do all work on exam pages
Answers accurate to within 10% will receive full credit
Default bipolar transistoe parameters:
npn: (beta)n = 100, VAn = 50 V, ISn = 10 16 A.
pnp: (beta)p = 50, VAp = 25 V, ISp = 10 16 A. q Default MOS transistor parameters:
NMOS: (mu)n C ox = 50 (mu)AV2, (lambda)n = 0.02V1, VTn = 1 V.
PMOS: (mu)p C ox = 25 (mu)AV2, (lambda)p = 0.02V1, VTp = 1 V. Problem #1. Matched Complementary Bipolar Transistor Design [12 points]
The cross sections, minority carrier concentrations, and circuit schematics are shown for matched npn
and pnp vertical BJTs, operated in the forwardactive region. file:///C/Documents%20and%20Settings/Jason%20Raft...20%20Fall%201993%20%20Howe%20%20Midterm%202.htm (1 of 5)1/27/2007 4:43:34 PM EECS 105, Midterm #2, Fall 1993 Given: all doping levels are matched and the emitter areas are identical
q NdE (npn) = NaE (pnp) q NaB (npn) = NdB (pnp) q NdC (npn) = NaC (pnp) q AE (npn) = AE (pnp) Given: the bias volatages for the two transistors are matched and both are in the forwardactive region
q VBEn = VEBp q VCEn = VECp file:///C/Documents%20and%20Settings/Jason%20Raft...20%20Fall%201993%20%20Howe%20%20Midterm%202.htm (2 of 5)1/27/2007 4:43:34 PM EECS 105, Midterm #2, Fall 1993 (a) [5 pts.] In order for the npn and the pnp transistors to have matched collector currents, ICn =  ICp ,
determine the numerical value of the base width of the pnp, WBp.
Given: the base width of the npn is WBn = 0.2 (mu)m, the electron diffusion coefficient (diffusivity) is
Dn = 20 cm2s1, and the hole diffusivity is Dp = 10 cm2s1  these are valid for the emitter, base, and
collector of each transistor.
(b) [5 pts.] In order for the npn and the pnp transistors to matched base currents, IBbn =  IBp ,
determine the numerical value of the emitter width of the pnp, WEp. This part is independent of part (a).
Given: the emitter width of the npn is WEn = 0.1 (mu)m, and Dn = 20 cm2s1, Dp = 10 cm2s1.
(c) [2 pts.] Which transistor has the smaller Early voltage, VA? Explain why in one sentence. Problem #2. TwoStage Transconductance Amplifier [24 points] Given: IREF = 100 (mu)A, VL = 0(DC), RS = 1 k(omega), RL = 400 k(omega)
MOSEFTs: (W/L)3,5,6,7 = 10 and (W/L)4 = 25
(a) [4 pts.] Find the collector currents IC1 and IC2. You can neglect the base currents IB1 and IB2, as is
customary for hand calculations. file:///C/Documents%20and%20Settings/Jason%20Raft...20%20Fall%201993%20%20Howe%20%20Midterm%202.htm (3 of 5)1/27/2007 4:43:34 PM EECS 105, Midterm #2, Fall 1993 (b) [4 pts.] Find the numerical value of the input resistance, Ri of this amplifier. If you couldn't answer
part (a), you can assume that IC1 = 50 (mu)A and that IC2 = 75 (mu)A for this part.
(c) [4 pts.] Find the numerical answer value of the output resistance, Ro of this amplifier. If you couldn't
answer part (a), you can assume that IC1 = 50 (mu)A and that IC2 = 75 (mu)A for this part.
(d) [4 pts.] Find the numerical value of the shortcircuit transconductance Gm of the amplifier. Again, if
you couldn't answer part (a), you can assume that IC1 = 50 (mu)A and that IC2 = 75 (mu)A for this part.
(e) [5 pts.] Find the numerical value of the laod current il, for a smallsignal input voltage vs = 2 mV. If
you couldn't solve parts (b), (c), and (d), asumme for this part that Ri = 80 k(omega), Ro = 500 k
(omega), and Gm = 7.5 mS.
(f) [3 pts.] What is the DC voltage at the base Q1? You can assume that VBE = 0.7V for the transistors
in the forwardactive region. Problem #3. CurrentSource Design [14 points] Given: (W/L)1 = (W/L)2 = (W/L)3 file:///C/Documents%20and%20Settings/Jason%20Raft...20%20Fall%201993%20%20Howe%20%20Midterm%202.htm (4 of 5)1/27/2007 4:43:34 PM EECS 105, Midterm #2, Fall 1993 (a) [5 pts.] Find (W/L)1 such that IREF = 20 (mu)A.
(b) [3 pts.] Find (W/L)4 such that IOUT = 50 (mu)A. If you couldn't solve part (a), assume that (W/L)1 =
10.
(c) [3 pts.] Find the numerical value of roc for this current source, assuming that IOUT = 50 (mu)A.
(d) [3 pts.] Assuming that the sourcegate voltage for transistor M4 is VSG4 = 1.4V. What is the largest
DC output voltage VOUT for which transistor M4 remains in the saturation region? Posted by HKN (Electrical Engineering and Computer Science Honor Society)
University of California at Berkeley
If you have any questions about these online exams
please contact mailto:examfile@hkn.eecs.berkeley.edu file:///C/Documents%20and%20Settings/Jason%20Raft...20%20Fall%201993%20%20Howe%20%20Midterm%202.htm (5 of 5)1/27/2007 4:43:34 PM ...
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This note was uploaded on 05/17/2009 for the course EE 105 taught by Professor Kingliu during the Spring '07 term at University of California, Berkeley.
 Spring '07
 KingLiu
 Electrical Engineering

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