Testing an analogue circuit using a complementary signal set

The research undertaken aims to provide a test pattern that can fulfil the requirements for mixed signal test using a digital signal processing test system. The signals used for an initial study on a simple analogue circuit are a class of nonperiodic pseudo random signals called Complementary Signals. In order to assess the fault coverage achievable with these an HSPICE simulator was used to investigate the circuit under test under ideal operating conditions and with the presence of single `hard´ faults The test stimulus comprised a relatively simple 2×8 (signals×bits) complementary signal set. Supply current and output voltage simulation results were processed using several methods to calculate the fault coverage achieved. Fault coverages were high, especially for supply current monitoring for which values of 100% were recorded. Provided complementary signals were suitable they would allow a digital signal processing (DSP) based test system to be used, removing the need for separate analogue and digital test equipment and resulting in a unified piece of test equipment that could monitor the circuit responses and also provide the test stimulus