single-stage integrated- circuit amplifiers. ic biasing 6.3.1 the basic mosfet current source...
DESCRIPTION
IC Biasing MOS Current-Steering Circuits Effect of V o on I o Difference Q 2 and Q 5 Current Source, Current SinkTRANSCRIPT
Single-Stage Integrated-Circuit Amplifiers
IC Biasing6.3.1 The Basic MOSFET Current Source
2
1
'1 2
1tnGSnD VV
LWkI
RVVII GSDD
REFD
1
2
2
'2 2
1tnGSnDO VV
LWkII
1
2
)/()/(
LWLW
II
REF
O
SATURATION
IC BiasingMOS Current-Steering Circuits
1
22 LW
LWII REF
1
33 LW
LWII REF
4
545 LW
LWII
tnGSSSDD VVVVV 132 ,Effect of Vo on Io
Difference Q2 and Q5
Current Source, Current Sink
IC BiasingBJT Circuits
Current Transfer Ratio
mQQ
II
C
O 1
2
of EBJ of Area of EBJ of Area
Case 1: m = 1
21
121
C
C
REF
O
I
III
C
CREFIII 2
Case 2:
11
mm
II
REF
O
Output Resistance
O
A
O
OO I
VIVR 2
2
111 A
BEOREFO V
VVmmII
IC BiasingBJT Circuits – Current Steering
Effect of Vo on Io
RVVVVI BEEBEECC
REF21
REFII 23
REFII 34
VVV CC 3.0collector
High-Frequency Response The High-Frequency Gain Function
)()( sFAsA HM
gain DCor frequency -low gain, midband :MA
PnPP
ZnZZH sss
ssssF
/1/1/1/1/1/1)(
21
21
S 0, F(s) 1
High-Frequency Response Determining the 3-dB Frequency fH
121
21
/11
/1/1/1/1/1/1)(
PPnPP
ZnZZH ssss
ssssF
A dominant pole exits if the lowest frequency pole is at least two octaves (a factor of 4) away from the nearest pole or zero.
1PH
High-Frequency Response Determining the 3-dB Frequency fH (cont.)
21
21
/1/1/1/1)(
PP
ZZH ss
sssF
2222
22222
21
21
/1/1/1/1
)(PP
ZZjFH
2222
2222
21
21
/1/1/1/1
21
PP
ZZ
HH
HH
22
21
2
22
21
2
22
21
42
221
2
22
21
42
221
2
111
111
/111
/111
PPH
ZZH
PPHPP
H
ZZHZZ
H
22
21
22
21
22111ZZPP
H
High-Frequency Response Determining the 3-dB Frequency fH (cont.)
44
5
104/110/110/1)(
ss
ssFH
High-Frequency Response Using Open-Circuit Time Constants for the
Approximate Determination of fH
nn
nn
H sbsbsbsasasasF
221
221
11)(
PnPP
b
111
211
Difficult to obtain poles and zeros
n
iioiRCb
11
Rio: Seen by Ci when reducing all other capacitance to zero and reducing the input signal to zero
iioi
HP RCb
b 111
111
High-Frequency Response Example 6.6
Small Signal Equivalent Circuit for CS Amplifier
Frequency Response for CS Amplifier032
gd
oxgs
C
WLCC
oxgdgs WLCCC21
Triode
Saturation
High-Frequency Response Example (cont.)
VmAg
pFCC
kRkRkR
m
gdgs
Linsig
/4
1
33.3,420,100 '
H
sigoM
f
VVA /
High-Frequency Response Example (cont.)
)( 'Lm
sigin
in
sig
oM Rg
RRR
VVA
High-Frequency Response Example (cont.)
nsRC
kRRR
gsgsgs
sigings
8.80108.80101
8.80100||420||312
High-Frequency Response Example (cont.)
sigin
xgsin
gs
sig
gsx
RRR
RIVRV
RV
I
||'
'
MRRgRRIVR
RVV
VgI
LmLx
xgd
L
xgsgsmx
16.1''''
'
ns
RC gdgdgd
11601016.1101 612
kHz3.1282
krad/s8061
HH
gdgsH
f
High-Frequency Response Miller’s Theorem
ZKVVI
ZVI 11
1
11
Z
KVVIZKV
ZVI 11
2
1
2
22
00
High-Frequency Response Miller’s Theorem --- Example
?/,1or 1 sigO VVpFMZ
High-Frequency Response Miller’s Theorem --- Example (cont.)
Mk
K
ZZ
kkK
ZZ
99.0
10011
100011
9.91001
10001
2
1
High-Frequency Response Miller’s Theorem --- Example (cont.)
10011
111
10011
1
2
1
sC
K
ZZ
sCK
ZZ
The CS and CE Amplifiers with Active Loads
The CS and CE Amplifiers with Active Loads