Patent ID: 6374204
Filing Date: 2002-04-16
Classification: G06F

Abstract:
A method for designing an amplifier circuit having a transistor having known circuit characteristics, the method comprising the steps of:modeling the transistor circuit by, (a) inputting into a processor a known transistor circuit input value; (b) sampling a gate-to-source voltage from the known circuit input value to obtain sample voltage values; (c) estimating an initial drain current having frequency components in response to the sample voltage values; (d) generating a drain-to-source voltage vector having frequency components in response to the frequency components of the initial drain current vector; (e) generating an initial time domain vector of the drain current from the frequency components of the drain-to-source voltage; (f) determining a time domain drain-to-source voltage at least in part by performing an inverse FFT of the frequency components of the drain-to-source voltage; (g) generating a current gradient vector having gradient frequency components as a function of the sample voltage values and the initial time domain vector of the drain current; (h) generating a recursion matrix in response to the gradient frequency components; (i) performing a fast Fourier transform of the initial time domain vector of the drain current; (j) computing an analytical representation of a Jacobian matrix of an initial output value using the time domain vector of the drain current; (k) updating the initial drain current vector estimate using the recursion matrix to obtain an updated current vector; (l) calculating a convergence factor based on a difference between the updated drain current vector and the initial drain current vector; (m) displaying the convergence factor; (n) testing the convergence factor to determine whether the initial drain current vector and the updated drain current estimate vector have converged; (o) repeating steps of (c) through (n) until the updated drain current and the initial drain current have converged; (p) when the updated drain current vector and the initial drain current vector have converged, performing an inverse fast Fourier transform of the drain current vector and the drain-to-source voltage; (q) calculating a final drain current and a final drain-to-source voltage of the transistor circuit in response to the updated drain current vector and the time domain drain-to source voltage; (r) displaying on an output device the final drain-to-source voltage and the final drain current to form a transistor model; and designing and testing the amplifier circuit in response to the transistor model.