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EE141EECS141 1Lecture #22

EE141-Fall 2012Digital Integrated Circuits

Lecture 22Domino Logic

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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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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