Download Early Voltage - Microelectronic Devices and Circuits - Solved Exam and more Exams Microelectronic Circuits in PDF only on Docsity! UNIVERSITY OF CALIFORNIA, BERKELEY
College of Engineering
Department of Electrical Engineering and Computer Sciences
EE 105: Microelectronic Devices and Circuits Fall 2009
MIDTERM EXAMINATION #2
16/29/2009
Time allotted: 75 minutes
NAME:
STUDENT ID#:
INSTRUCTIONS:
1.
SHOW YOUR WORK. (Make your methods clear to the grader!)
2. Clearly mark (underline or box) your answers.
3.
4. Unless specified otherwise, include EARLY effect in your analysis.
Specify the units on answers whenever appropriate.
SCORE: 1 /16
2 /16
3 /18
Total /50
PHYSICAL CONSTANTS
Description Symbol Value
Electronic charge g 1.6x10? C
Boltzmamn’s constant & 8.62x10°
eViK.
Thermal voltage at Ve= 0.026 V
300K kTlq
USEFUL NUMBERS
Vin(10) = 0.060 V at T=300K
exp(30) ~ 10°
PROPERTIES OF SILICON AT 300K
Description
Band gap energy
Intrinsic carrier
concentration.
Dielectric permittivity
Symbol Value
Eg 1.12 eV
Ki 10” om?
&i 1.0x10°?
Fiem
PROB 2. BIT Amplifiers and Cascodes [16 pts].
a} [6 pts] What is the gain of the following amplifier? Where would you use such an amplifier?
Why? Ignore the early effect.
Re
Av = ——
—- EL
Van + Fe
used as @ buhfrr Stage
out ji gan be
betwen &@ CE stage md a Feil bad.
; 2 rma Lesyades
Reasons Pulting a Ce Stage Uvectly fo a emace [0h eer
the Gor, Ts parhelar stage gives My ope
umpedanies and IR output yeydctonre’ teereby matting bt
pw CAUSE EL rey ‘¢ ing
b} [2 pts] How do cascodes help in amplifier design? \ umn p aa OVE, wihoren CE KEE
a Wek XD smatt trrd-
@ astades boost the guiput impedance thereby ener ce gers,
the gam:
c} [4 pts} What is the maximum output impedance of the following cascade?
f Ro ~
fy
VAS Raf Om fe a
Vor a, Rout = Yo + (i amy) { TM 2 i
Vb2 Qe | Ro Ry = Yop (ix Sregl a) (ics it ey)
Yess as % rq, Yon (oan Va) x
a) Rew ® gyn ter
oe
Since, RedS Vr, — Rail Ye, My
d) [4 pt} Explain why the following is not a good cascade. How will you change the design to
obtain a larger small signal gain?
9
tiny)
t= 4, Vin - ba 2 {
~ - ee g : y
=> 14 Siig, (Yes! 52) | ue = Sone Yun
bt
tr > Glvrall Qaim = Vin —
. ae ‘
Jing Sate)
Via, ee
vin & Gon, (Yop th Ver
ba Gm, Voi
Hence auerad | gan: iS very Yat.
s rly Chao e.
Woy Te sedwe This problum 1S ky vavtey Ueares
An Casy
Vol gnd Vin | 1
fog ++ amaren) CMR) |
ag Viet
Ave- Sm
— he oS
Se lute Aa OT fy Ria VE
PROB 3. Current mirrors and Frequency Response. [18 pts]
a) {3 pts] Neglecting base currents find foopy1 a5 a function Of fret
copyt
Current
Mirror
b} [3 pts] Why is the following not a good mirror?
Vec
REF Since Vy ts Fined, ’Rer
R thange ve demp uacil a tterk
Qrer ad + Q,
j rad uaa thon t
. -T “x Lupyp. Note Veak wa
ine diode Ermnectien Ree Spex
aqua by ave eamplity vider
Vy for Cpep Com bt doth ent
pehrw ak fis
