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EE141EECS141 1Lecture #22
EE141-Fall 2012Digital Integrated Circuits
Lecture 22Domino Logic
EE141EECS141 2Lecture #22
AnnouncementsProject phase 2 due Friday Phase 3 out this Friday
Homework #8 out next Tues., due following Tues.
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Class Material
Last lecture Multipliers
Today’s lecture Domino logic
Reading Chapter 7
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Domino Logic
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Domino Logic
In1In2 PDNIn3
Me
Mp
Clk
Clk Out1
In4 PDNIn5
Me
Mp
Clk
ClkOut2
Mkp1 11 0
0 00 1
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Why Named Domino?
Clk
Clk
Ini PDNInj
IniInj
PDN Ini PDNInj
Ini PDNInj
Like falling dominos!
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EE141EECS141 7Lecture #22
Properties of Domino Logic
Only non-inverting logic can be implemented Very high speed static inverter can be skewed, only L-H transition
critical Input capacitance reduced – smaller logical effort
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Domino Logic LE
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Domino Logic LE (skewed static gate)
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Buffer “Average” LE
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Optimal EF/stage with DominoDomino buffers are faster than static
CMOS inverters Is optimal EF/stage for a chain of domino
gates still 4?
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Example
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Designing with Domino Logic
Mp
Me
VDD
PDN
Clk
In1In2In3
Out1
Clk
Mp
Me
VDD
PDN
Clk
In4
Clk
Out2
Mr
VDD
Inputs = 0during precharge
Can be eliminated
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Footless Domino
The first gate in the chain needs a foot switchPrecharge is rippling – short-circuit current
VDD
Clk MpOut1
In11 0
VDD
Clk MpOut2
In2
VDD
Clk MpOutn
InnIn31 0
0 1 0 1 0 1
1 0 1 0
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Footless Domino
Can mitigate short-circuit current by alternating between footed and unfooted domino
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Footless Domino
To eliminate the short-circuit current, can delay the clock for each stage
VDD
Clk MpOut1
In11 0
VDD
Clk MpOut2
In2
VDD
Clk MpOutn
InnIn31 0
0 1 0 1 0 1
1 0 1 0
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Differential (Dual Rail) Domino
A
B
Me
Mp
Clk
ClkOut = AB
!A !B
Mkp ClkOut = AB
Mkp Mp
Allows inverting gates to be built
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np-CMOS
In1In2 PDNIn3
Me
Mp
Clk
Clk Out1
In4 PUNIn5
Me
MpClk
Clk
Out2(to PDN)
1 11 0
0 00 1
Only 0 1 transitions allowed at inputs of PDN Only 1 0 transitions allowed at inputs of PUN
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NORA Logic
In1In2 PDNIn3
Me
Mp
Clk
Clk Out1
In4 PUNIn5
Me
MpClk
Clk
Out2(to PDN)
1 11 0
0 00 1
Fast, but EXTREMELY sensitive to noise!
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Next Lecture
Flops and Latches
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