Timing Abstraction

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