Approximation algorithms for low-frequency characteristics of bipolar transistors

A bipolar transistor model utilizing empirically derived hybrid parameters is presented and different approximation techniques are compared. Polynomials with positive exponents, and with both positive and negative exponents, are compared for effectiveness in approximation of monotonically increasing functions or decreasing functions over the entire range or initial range of parameter values of interest. The sensitivity of algorithms utilizing either type of polynomials to round-off error is discussed, on the basis of empirical data. Computational flow charts are included. Rational-polynomial (Lagrange polynomial) and least-squares approximations are discussed, in addition to stabilizer projection programs and both small-signal and large-signal computations.