Patent ID: 7576550

Claim:
A parametric test system for testing devices in dice in a semiconductor wafer, each die having a plurality of pads for electrically connecting to the device in the die, comprising: a) a tester having a plurality of input/output lines for providing and receiving electrical signals during a device test, b) a wafer prober having probe contacts for engaging pads on a die, c) multiplexer circuitry coupled to receive electrical signals on the input lines from the tester and to provide the electrical signals to the wafer prober, the multiplexer circuitry comprising a plurality of networks of automated switches, each network of automated switches having a plurality of inputs and a plurality of outputs and is configured such that any of the plurality of inputs to that network of automated switches may be connected to any of the plurality of outputs of that network of automated switches, and multiplexer input stage circuitry, wherein the multiplexer input stage circuitry provides the electrical signals from the tester to the networks of automated switches via the multiplexer input stage circuitry, the multiplexer input stage circuitry being configured such that each signal provided from the tester may be selectively electrically coupled to any one of the plurality of networks of automated switches but, for each network of automated switches, that signal can only be coupled to one predetermined input of that network of automated switches.