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Timing Abstraction. Pirouz Bazargan Sabet. Patricia Renault. Dominique Le Dû. Abstraction. Netlist Tr, C, R. Functional Abstraction. Netlist of Gates, C, R. Timing Abstraction. Gate Delays. a. b. a. F up = b. + a. b. F up = F down. Functional Abstraction. - PowerPoint PPT Presentation
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Pirouz Bazargan Sabet ValMem - March 2010
Timing Abstraction
Pirouz Bazargan Sabet
Patricia Renault
Dominique Le Dû
Pirouz Bazargan Sabet ValMem - March 2010
Functional Abstraction
Netlist Tr, C, R
Netlist of Gates, C, R
Abstraction
Timing Abstraction
Gate Delays
Pirouz Bazargan Sabet ValMem - March 2010
a
a
b
Fdown = a . b
b
Fup = b + a
Functional Abstraction
Fup = Fdown
follow the current paths
Pirouz Bazargan Sabet ValMem - March 2010
a
b
c
d
Functional Abstraction
conflict
tri-sta
teFup . Fdown = c.d.(ab)
Fup + Fdown = c.d
c=d
Fup = db + caFdown = db + ca
Fup = cb+ ca
functional view timing view
Pirouz Bazargan Sabet ValMem - March 2010
Delay Evaluation
xi y
Accurate delay using electrical simulation
Simulation of each configuration : 1 input
switching while others are in steady state
Pirouz Bazargan Sabet ValMem - March 2010
a
b
c
d
Fup = db + caFdown = db + ca
Fup = cb+ ca
a b c dx x x
x xx
xx x
x x x
Delay Evaluation
Pirouz Bazargan Sabet ValMem - March 2010
Include the gates until
reaching the sources
of correlation
sources of correlation
size some correlations are not useful number of configurations
Delay Evaluation
Pirouz Bazargan Sabet ValMem - March 2010
Explore the supergate to
identify the configurations
to be simulated
sources of correlation
Delay Evaluation
Functional exploration
Pirouz Bazargan Sabet ValMem - March 2010
a
b
c
d
Fup = db + caFdown = db + ca
Fup = cb+ ca
a b c dx x x
x xx
xx x
x x x
Delay Evaluation
x x
Pirouz Bazargan Sabet ValMem - March 2010
Functional correlation :
Delay Evaluation
a b
x
inputs
configstiming correlation
transition delay between a and b depends on the
delay of the gates involved in the supergate
Electrical simulations should be
done regarding the gates’ graph
Pirouz Bazargan Sabet ValMem - March 2010
Delay Evaluation
Timing dependency