US 5,673,420 AGranted

Method of generating power vectors for cell power dissipation simulation

AssigneeMotorola, Inc.

InventorsAlberto J. Reyes, Gary K. Yeap, James P. Garvey

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Abstract

A method of generating power vectors to calculate power dissipation for a circuit cell is provided. The method involves formulating the Boolean equations (30) that describe the logical operation for a circuit cell (10). Primitive power vectors that cause an output to transition are generated (32) using Boolean difference functions. Internal power vectors that cause an internal node to transition without transitioning the output are generated (34) using Boolean difference functions. Static power vectors with all possible steady state inputs are also generated (36). The power vectors are minimized (38) to eliminate redundant vectors. The resulting power vectors can be used in a circuit simulation in evaluating (40) the power dissipation of a designed logic circuit.

Claims14

Dependent claims

A method of generating power vectors for power dissipation simulation of a cell, comprising the steps of:

generating primitive power vectors that cause an output of the cell to transition by,
(a) defining a Boolean function describing logical operation of the cell,
(b) generating a Boolean difference function for each combination of output y and x.sub.i of the cell,
(c) expressing said Boolean difference function in sum-of-products notation to isolate product terms,
(d) generating first and second power vectors for each of said product terms based on said Boolean difference function,
(e) incrementing a variable x.sub.j through inputs x.sub.i,
(f) assigning said variable x.sub.j of said first vector as rising when x.sub.j =x.sub.i,
(g) assigning said variable x.sub.j of said second vector as rising when x.sub.j =x.sub.i,
(h) assigning said variable x.sub.j of said first and second vectors as logic one when x.sub.j .noteq.x.sub.i and said product term is uncomplemented,
(i) assigning said variable x.sub.j of said first and second vectors as logic zero when x.sub.j .noteq.x.sub.i and said product term is complemented, and
(j) assigning said variable x.sub.j of said first and second vectors as don't care when x.sub.j .noteq.x.sub.i of said product term is absent,
generating internal power vectors that cause an internal node to transition without transitioning said output of the cell;
generating static power vectors for the cell;
providing a minimal set of power vectors from said primitive power vectors and said internal power vectors and said static power vectors;
storing the minimal set of power vectors from said primitive power vectors, said internal power vectors, and said static power vectors in a computer-readable medium;
performing a circuit simulation with said minimal set of power vectors to determine power dissipation for the cell;
implementing a layout of a circuit in accordance with the circuit simulation;
and
generating a set of photomasks in accordance with the layout of the circuit.

16 more elements

A method of generating internal power vectors that cause an internal node to transition without propagating to an output of a cell, comprising the steps of:

generating primitive power vectors that cause an internal node to transition by,
defining a Boolean function describing logical operation of the cell;
generating a first Boolean difference function for each combination of internal node z and input x.sub.i of the cell;
expressing said first Boolean difference function in sum-of-products notation to isolate product terms;
generating first and second power vectors for each of said product terms based on said first Boolean difference function;
incrementing a variable x.sub.j through inputs x.sub.i ;
assigning said variable x.sub.j of said first vector as rising when x.sub.j =x.sub.i ;
assigning said variable x.sub.j of said second vector as falling when x.sub.j =x.sub.i ;
assigning said variable x.sub.j of said first and second vectors as logic one when x.sub.j .noteq.x.sub.i and said product term is uncomplemented;
assigning said variable x.sub.j of said first and second vectors as logic zero when x.sub.j .noteq.x.sub.i and said product term is complemented;
assigning said variable x.sub.j of said first and second vectors as don't care when x.sub.j .noteq.x.sub.i and said product term is absent;
generating static power vectors for the cell;
providing a minimal set of power vectors from said primitive power vectors and said internal power vectors and said static power vectors;
storing the minimal set of power vectors from said primitive power vectors, said internal power vectors, and said static power vectors in a computer-readable medium;
performing a circuit simulation with said minimal set of power vectors to determine power dissipation for the cell;
implementing a layout of a circuit in accordance with the circuit simulation;
and
generating a set of photomasks in accordance with the layout of the circuit.

15 more elements

Dependencies are inferred from the claim text.