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Unformatted text preview: EE 105, Midterm #2, Fall 1992 EE 105, Fall 1992
Midterm #2
professor Howe Closed book and notes; one formula sheet(both sides)
Do all work on exam pages
You have 50 min; use your time wisely
Problem #1
Bipolar Amplifier
Given: npn: ßn=100, Early voltage VAn=100V
pnp: ßp=20, Early voltage VAp=50V
The voltage VIN is adjusted so that the DC output voltage level VOUT=0V.
The resistances roc of the current sources are infinite. The various smallsignal resistances referred to in
parts(b)(d) are defined on the schematic.
If you do not have time to find numerical values, leave the answer in symbolic formbe sure to include
subscripts to identify which transistor the parameter is for. (a) (3 pts) Find the DC values of VCE1, VEC2, and VCE3. You can neglect base currents.
(b) (3 pts) Find the numerical value of the input resistance Ri.
(c) (4 pts) Find the numerical value of the output resistance of the first stage, Ro1.
(d) (4 pts) Find the numerical value of the output resistance Ro. Given: the output resistance of the
second stage is Ro2=500KOhm.
(e) (4 pts) Find the numerical value of the smallsignal voltage gain A1 between the voltage source vs
and the collector of Q1: A1=vc1/vs file:///C/Documents%20and%20Settings/Jason%20Raft...20%20Fall%201992%20%20Howe%20%20Midterm%202.htm (1 of 3)1/27/2007 4:43:34 PM EE 105, Midterm #2, Fall 1992 Problem #2
(18 points) fancy MOS current source Given for all transistors: (W/L)=32, mobility*Cox=100microA/V^2, VTn=1V, lambdan=0.01.
(a) (5 pts) Find the numerical value of R(REF) such that the output current is IOUT=100 microA
(b) (3 pts) Find the numerical value of the drain voltage of transistor M2, VD3. If you could not solve
part(a), assume that R(REF)=25KOhm, which is (of course) not the correct answer to part(a).
(c) (5 pts) What is the minimum value of the output voltage VOUT for which all transistors are
saturated?
(d) (5 pts) Find the numerical value of the output resistance roc of the current source. Given:
gm*ro=800 for all transistors.
Problem #3 file:///C/Documents%20and%20Settings/Jason%20Raft...20%20Fall%201992%20%20Howe%20%20Midterm%202.htm (2 of 3)1/27/2007 4:43:34 PM EE 105, Midterm #2, Fall 1992 Given: baseemitter junction is forward biased, basecollector junction is reverse biased, the base
transport factor alpha(T)=1 (meaning that no recombination occurs in the base).
Given: Dn=20cm^2/s, Dp=10cm^2/s. The area of the baseemitter junction is: AE=10^(5)cm^2.
(a) (3 pts) What is the numberical value of the electron diffusion current density in the base(units: A/
cm^2)
(b) (3 pts) What is the numberical value of the hole diffusion current density in the emitter (units: A/
cm^2)
(c) (4 pts) What is the numberical value of the collector current IC?
(d) (4 pts) What is the numberical value of the current gain? 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%201992%20%20Howe%20%20Midterm%202.htm (3 of 3)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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