A simple but efficient analog computer for simulation of high-speed integrated circuits

An analog computer is described which performs transient simulation of nonsaturated transistor circuits with little expense of time. The computer contains models of bipolar transistors and Schottky-barrier diodes as well as variable capacitors and resistors, all realized in plug-in technique. The parameters of the semiconductor devices are directly and continuously adjustable. Therefore, no special knowledge is required to operate the computer. For the display, a dual-trace oscilloscope with low bandwidth is sufficient because the analog time range lies above 0.1 ms. Compared with the digital computer simulation, this analog method has the advantages of lower costs and less simulation time, the latter allowing fast interaction between designer and computer. The good accuracy of the described simulation method is demonstrated by comparing the simulated and the directly measured transient response of an integrated subnanosecond E/SUP 2/CL gate. Also it is shown how the delay time of this gate depends on the transistor parameters.