Signal switching in automated test system for the transfer function characterization

This paper is focussed on a low cost modular instrumentation system achievement. A GPIB interface target using VLSI specialized integrated circuits and several middle capabilities programmable instrument targets have been designed to provide a complete and versatile instrumentation system using a support bus to interconnect the different module-instrument STD backplane. A computer-based virtual instrument (VI) which can perform a dynamical characterization of DC-DC switching converters has been implemented using this modular instrument, the VI is devoted to the test of the PWM devices used as duty cycle controllers in the design of switched DC-DC converters. Such VI has been implemented using a switching module which has been designed as a plug-in card in the STD bus instrumentation system, performing both signal routing and data acquisition. As an example, Y/sub in/ and Z/sub out/ characterization of a PWM-based Boost converter have been obtained.