Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
平成17年度 前期 大学院
情報デバイス工学特論第5回
中里 和郎
基本CMOSロジック回路(2)
今回の講義内容は
William J. Dally and John W. PoultonDigital Systems EngineeringCambridge University Press, 1998
4.3.4~4.4.2 (pp. 191-215)の内容に従っ
ている
Basic FET Amplifiers Forms
inout
Load
Load
inout
in outLoad
VGG
Common Source Source Follower Cascode or Common Gate
voltage gain
current gain
X
X
○
○ ○
○
Source Follower
inout
1/ 22 S
out in TnIV V Vβ
⎛ ⎞= − − ⎜ ⎟
⎝ ⎠
Ld
S
VCtI
Δ=
inout
CL
CG
IS
基板バイアス効果により
1out
in
VV
Δ<
Δ
出力への駆動力が大きい入力への負荷が小さいCG の影響小
Vin
Vout
0VTn
Source Follower Logic
A
B C( )D A B C= ∧ ∨
not composable 繋げて回路を組むには、出力をレベル・シフトし増幅してやる必要がある
他の回路との組み合わせとして使う
Cascode
ID
in
outVGG
ID
in
out
ref
ID
replica-bias circuit
Vin = Vref
Vout = VGG
VGG
VX
Vin
Vout
0
2 DX GG Tn
IV V Vβ
= − −
VDD
GG TnV V−
VX = Vref
Cascode Logic
A
B
IDVGG
C A B= ∧
not composable
Cascoded Common-source Amplifier
ID
out
VGG
in
AA GG TnV V V≈ −
m1
m2
DCゲインの増加Miller 効果を消す
Current Mirrors
I1 I2
VGG
VO1/ 2
12GG Tn
IV Vβ
⎛ ⎞− = ⎜ ⎟
⎝ ⎠
( ) ( ) ( )22 11 1GG Tn O OI V V V I Vβ λ λ= − + = +
2 1
1OO
VrI Iλ
∂= =
∂
I1 I2
I1
I2 I3 I4
low-pass filter
Cascode Current Mirror
I1 I2
VG2
VO
VG1
( )22 2 1
2OO
G Tn
VrI V V Iλ
∂= =
∂ −
VO
I2
m1
m2
m1
m2
線形
線形 飽和
飽和
動作領域が狭くなる (headroom)
Source-Coupled Pair
I1 I2
V1 V2
VS
IS
ΔV = V1- V2
I1 , I2
0
IS
0
I1I2
1 2V V VΔ = − 1 2I I IΔ = −
1 2
2CV VV +
= 1 2
2 2S
CII II +
= =
mI g VΔ = Δcommon-mode
differential
( )m C S Tng V V Vβ= − −
Differential Load
Differential Voltage Differential CurrentSource-coupled pair
Differential Load
+ ΔV −I1 I2
V1 V2
VrIΔ
∂Δ=
∂ΔC
CC
VrI
∂=
∂
CC
VrIΔ
∂Δ=
∂C
CVr
IΔ
∂=
∂Δ
cross-impedance
C CC C
C
r rV Ir rV I
Δ
Δ Δ
⎛ ⎞⎛ ⎞ ⎛ ⎞= ⎜ ⎟⎜ ⎟ ⎜ ⎟Δ Δ⎝ ⎠ ⎝ ⎠⎝ ⎠
R R
Several Differential Loads
I1 I2V1 V2
I1 I2V1 V2
I1 I2V1 V2
I1 I2V1 V2
Resistor Current Mirror Cross-Coupled Infinite Impedance
rC R
rΔ R
1/gm
1/λI1
1/gm
−1/gm
1/2gm
∞
FET Resistor
I
V+
−
Triode
I
V+
−
Two-elements
V
I
Pass Gate FET Resistor
r0 r1 r2 r3
r0 , r1 , r2 , r3 = H or L
Digital Trimming
Simple Differential Amplifier
I1 I2out+out−
in+ in−
Vbias
Vbias
Vlow+−
Replica-bias Circuit
Gain
gm
rΔ
AΔ=gmrΔ
ΔVin=Vin+−Vin−0
Vout−Vout
Vout+
Vhigh
Source Coupled FET Logic
XOR
Vbias
B-
A+ A-
B+
out+out−
Bandwidth of Differential Amplifier
dr Cτ Δ=out+
in+
Vbias
in−
mA g rΔ Δ=
cutoff frequency
1 12 2 d
fr Cπτ πΔ
Δ
= =
gain bandwidth product(unity-gain frequency)
1 2m
d
gf A fCπΔ Δ= =
AΔ
fΔ f1
1ff
1 f
Gain
Regenerative Circuits and Clocked Amplifier
I
+ ΔV −
I1 I2
Cd Cd
V1 V2小さな信号 ΔV を高速でfull-swing に増幅
t = 0 Ι = 0 , ΔV =ΔV(0)
m
d d
gd V I Vdt C CΔ Δ
= = Δt > 0
( )0 expr
tV Vτ
⎛ ⎞Δ = Δ ⎜ ⎟
⎝ ⎠
dr
m
Cg
τ =
in+clk
clk
clk
clk
V1 V2in−
Complementary Clocked S/A
clk = low
in+ → V1in− → V2
clk = high
in+, in− → VDD , 0
pass gate
in+
clkclk
in−
V1 V2
Gate-Isolated S/A
clk
S1 S2
clk = low
S1, S2, V1, V2 : precharged
Static Latch
inclk
outS
clk
clk
Qualitative Circuit Analysis
1. Break all feedback loops and assign a direction to any
bidirectional circuit elements.
2. Identify basic circuit forms in the circuit and partition the
circuit into these components.
3. Identify region(s) of operation for each device.
4. Describe the open-loop behavior of the circuit.
5. Describe the closed-loop behavior of the circuit.
Qualitative Analysis of a Differential Amplifier
in+ in−
out+out−
Differential Load
Source-Coupled Pair
Current mirror
Voltage Divider
Qualitative Analysis of a Voltage-Controlled Oscillator
in
Current mirror
Current source
Inverters
Feedback
Power Dissipation of a Static CMOS Gate定常状態 どちらかのトランジスタがOFF
消費電力小 (サブスレッショルド電流x電源電圧)
ON ⇔ OFF の切り替え時に電力を消費
C
出力 OFF → ON のエネルギー消費量
( ) ( )2
0 2
DDVDD
SW DD C DD C CCVE V V Idt V V CdV= − = − =∫ ∫
= 出力 ON → OFF のエネルギー消費量
1サイクルのエネルギー消費量= CVDD2
消費電力 = C VDD2 KD fck
KD : duty factor ~ 0.15fck : clock frequency
Energy-Delay Product
( )22DD DD
DSS DD T
V C VCI V V
τβ
= =−
2cy DDE CV= ( )
32
22 DD
cyDD T
VCEV V
τβ
=−
VT
VDD
cyE τ
レポート(5)
1.右の Chappell Amplifier の動作を説明せよ
Vout+−
Vin
2.下の3つの回路を抵抗として用いた場合について I-V 特性を示せ。次の範囲でVが変化するとき、どの
回路を用いるのが良いか?(1) GND に近い小電圧(2) GNDからVctrl までの電圧(3) GNDからVDDまでの電圧
V VI I
VI
VctrlVctrl Vctrl
(a) (b) (c)