Patent ID: 7818158
Filing Date: 2010-10-19
Classification: G06F

Abstract:
1. A method of simulating a circuit containing an analog component, the method being performed in a computer, the method comprising: creating an RC tree representing a group of transistors in the analog component, each of the transistors being represented as a variable resistance in the RC tree; creating a piece-wise linear lookup table for a transistor in the group of transistors, the piece-wise linear lookup table containing a set of gate-to-source voltages and a factor corresponding to each gate-to-source voltage within the set, the factor being representative of a channel resistance of the transistor at the corresponding gate-to-source voltage; determining an operative gate-to-source voltage of the transistor as a first symbolic expression comprising a plurality of real-valued input voltages corresponding to a plurality of logical conditions; using the piece-wise linear lookup table to determine the channel resistance of the transistor at the operative gate-to-source voltage, as a second symbolic expression comprising a plurality of resistances corresponding to the plurality of logical conditions, each resistance being obtained by applying a corresponding real-valued input voltage in the first symbolic expression to said table; using the second symbolic expression to compute a voltage at a node of the analog component, the voltage being represented symbolically as a third symbolic expression comprising the plurality of logical conditions and a plurality of real-valued output voltages, each real-valued output voltage being computed based on the second expression and based at least partially on a supply voltage and a ground voltage of the analog component; and storing said third symbolic expression in a memory of said computer.