100 MHz circuit pack test system: a reality

A high-performance 100-MHz prototype test system for in-circuit or functional testing of complex high-speed digital circuit packs is described, including the test fixture, pin electronics, and the system software. The high-speed test system (HSTS) uses a high-frequency fixture in which the twisted-wire pair of the conventional fixtures is eliminated by providing a shielded fixed-length and controlled-impedance path from the driver/sensor to the board under test, thus eliminating noise and crosstalk in high-frequency applications. Signal reflections and timing skews are also minimized. The test system´s pin electronics channels (one drive or sense channel per test pin, up to 512 channels) contain a GaAs driver which is capable of backdriving at up to 1 A, with an output swing from -2 V to 10 V and a slew rate of 5 V/ns. HSTS supports high-level user-transparent operations for less experienced test operators. At the same time, for more experienced users, it provides low-level access to the hardware through HSTS driver options and application programs written in C