and an activity factor = 0.05 for memory arrays. Estimate dynamic power consumption per MHz.
Neglect wire capacitance and short-circuit current.
In 90nm process,
λ
=0.05μm
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
(
)
9
log
9
2
1 10
20%
10
0.05
2
200
1 10
80%
4
0.05
2
320
0.1
200
0.05
320
1.0
36
ic
memory
dynamic
C
m
fF
m
nF
C
m
fF
m
nF
P
f
mW
MHz
λ
μ
λ
μ
λ
μ
λ
μ
=
×
×
•
•
•
=
=
×
×
•
•
•
=
=
×
+
×
×
×
=
Problem 3
The figure below shows two cases with waveforms “a” and “b” applied to the circuit. Assume
the capacitor C
L
is initially discharged and the output time constant is very small.
For each case,
find the energy characteristics at time t
1
:
1.
Energy stored on the capacitor C
L
.
2.
Energy dissipated in the switching transistor.
3.
Total energy supplied by node b.
(Note: assume short circuit and static power dissipation are negligible)
a
b
out
C
L
V
0
b
V
0
a
V
0
V
0
b
a
Case 1
Case 2
time
time
time
time
t
1
t
1
Fig. 1.
Proposed schemes for energy comparison.
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Case 1
5.1 Energy stored on the capacitor C
L
(t0 is the time point where signal “a” toggles)
1
1
1
0
0
0
0
2
1
2
L
t
t
t
out
C
VDD
OUT
VDD
OUT
L
OUT
t
t
VDD
L
OUT
OUT
L
DD
dV
E
i
V
dt
i
V
dt
C
V
dt
dt
C
V
dV
C V
=
•
=
•
=
•
=
=
∫
∫
∫
∫
5.2 Energy dissipated in the switching transistor
1
1
1
0
0
0
0
2
(
)
(
)
(
)
(
)
1
2
t
t
t
out
Dis
VDD
DD
OUT
VDD
DD
OUT
L
DD
OUT
t
t
VDD
L
DD
OUT
OUT
L
DD
dV
E
i
V
V
dt
i
V
V
dt
C
V
V
dt
dt
C
V
V
dV
C V
=
•
−
=
•
−
=
•
−
=
−
=

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- Spring '10
- bashir
- Energy, Transistor, AOI gate, complex AOI gate
-
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