Parallel Loopback Test of Mixed-Signal Circuits

Parallel testing of mixed-signal circuits has been considered a difficult task due to the limited resources in generating and analyzing multiple analog signals. A number of methods have been proposed to perform parallel testing of mixed-signal circuits using built-in test circuitry; however, these techniques are vulnerable to fault masking issues which may degrade the test accuracy. This paper presents an efficient parallel test algorithm for mixed-signal circuits based on a loopback test method. Multiple DUTs (devices under test) are loopbacked externally on a loadboard which is loaded with a simple analog adder and an RMS detector. The performance parameters of each DUT are calculated separately from the composite responses, while removing the effect of fault masking. Parallelism is increased by sharing common test equipment and a DUT loadboard among the multiple DUTs. The mathematical theory and simulation results are presented to validate our algorithm.