Anthony Li Milan Shah MOSFETs NMOS PMOS MOSFET Operating Point Three regions of operation Cutoff V G lt V T I D 0 LinearTriode V G gt V T V DS lt V GS V ID: 724850
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Slide1
HKN ECE 342 Review Session 2
Anthony Li
Milan ShahSlide2
MOSFET’s
NMOS
PMOSSlide3
MOSFET Operating Point
Three regions of operation:
Cutoff (V
G
< VT
): ID = 0Linear/Triode (VG > VT, VDS < VGS - VT):
Saturation (V
G
> VT, VDS > VGS - VT): Note:
Slide4
MOSFET Incremental Model
Transconductance:
Slide5
Gain Calculation
A
v
= -G
MRoutG
M = Small signal transconductance, ratio of iout to vin ROUT = Equivalent incremental output resistanceSlide6
Common Amplifier Topologies
Diode-tied Transistor
Common Source/Drain/Gate
Common Source with Degeneration
Common Drain with Modulation
CascodeDiode Tied TransistorSlide7
Diode-Tied Transistor
R
OUT
=
for
or
Diode Tied TransistorSlide8
Common Source/Drain/Gate
Slide9
Degeneration
When a resistance is “viewed” through the drain, it appears bigger by a factor related to the transconductance.
Slide10
Modulation
Resistances seen through the source seem smaller:
for g
m
r
ds
>> 1
Slide11
Cascode
Slide12
BJTSlide13
Regions of Operation
Three regions of operation:
Cutoff: V
E
> VB < VC
Saturation: VE < VB > VCForward Active: VE > VB > VC
V
T
= kt/qIC = ꞵIBIE = IC + IBꞴ = gmR𝜋Slide14
BJT Small Signal ModelSlide15
Terminal Impedance
R
C
=
ro
RB = RℼRE =
Diode-Tied =
Diode Tied TransistorSlide16
Common Emitter/Collector/Base
Slide17
Degeneration
When a resistance is “viewed” through the collector, it appears bigger by a factor related to the transconductance.
R
IN
= R
B
+R
𝜋
+(ꞵ+1)RE Slide18
Modulation
Resistances seen through the Emitter seem smaller.
Slide19
Bode Plots
Magnitude
Pole: Roll down by 20
db
/dec, 6 db/oct
Zero: Roll up by 20 db/dec, 6 db/octPhase: arctan(ω/ωp)Usually -90° for poles, +90° for zeros
ω
ugf
= 20log|An| * ωpn where n is the pole located before unity gain frequencySlide20
Miller Effect
Slide21
Problem 1: Midterm 3 Fa17Slide22
Problem 2: Midterm 2 Fa16 Slide23
Problem 3: Midterm 2 Fa16
A.
,
B. Refer to solutions