ECE 4420 – Spring 2004 Page 1
Homework No. 11 – Solutions
Problem 1 – P7.15
OUT OL
XDDT
VV
VV V
=
=−
First, let’s find the required change in voltage:
()()
2
OUT DD OL
XDDT DDT T
VVV
VVV VV V
∆=−
∆= + − − =
Now, let’s set up the clock feedthrough equation and solve for Cb:
2
2
b OUT
X
bX
XX TX
b
OUT X DD OL T
CV
VCC
VC VC
CVVVVV
∆
∆= +
∆
==
∆−∆ −−
Problem 2 – P8.4
To compute the device sizes, start
with the access transistor and the pull-down
transistor:
We can compute the needed size of
M3 to deliver 300uA:
22
()
(8)(1.6)(1.8 0.5 0.5) 300
( ) (1.8 0.5 0.5) 1.2
0.75
L sat ox DD OL TL L
cell
DD OL TL CN L
L
WCV VV W
I
A
VVV EL
Wm
ν
µ
µ
−− −−
===
−− + −− +
≈
Now determine the minimum WD for the pull-down transistor:
()
()
22
62
()
2( )
1
(270)(1.6 10 ) 0.5
1.8 0.5 0.5
0.5 2
11.2
20.4(min)
Nox OL Lsatox DD OL TL
D
DD T OL
DD OL TL CN
OL
CN
D
cell
D
D
CVWCVVV
WVVV
LVVVEL
V
EL
WI
L
WWm
L
µν
µ
−
−−
∴
−−=
−− +
+
×−−=
+
≈=
M1
M3
Vdd
b
1.8V
1.8V
1.8V
0.5V
