All of the stand-alone Rg testers incorporate the FET gate parameter tester board with a relay matrix and a Kelvin test circuit. The Kelvin test is to check the continuity of the force and sense contacts onto the pins of the device under test. Communication with the tester is through a high speed serial link.

This third variant adds a voltage bias circuit and the ability to drive up to eight external relays on the handler interface. This unit keeps the Kelvin test circuit and can connect the device source and drain together. This board is designed to test only a single device which allows us to minimise any extra stray capacitance and inductance in the measurement path.

One semiconductor manufacturer wanted to do Rg tests with the gate under forward bias while a second manufacturer wanted the tests done with the drain biased. This had to be achieved without compromising the accuracy of the test system and adding as little to the total test time as was reasonably feasible. The board pictured will bias n-channel or p-channel devices with up to 10V on the gate or 30V on the drain.

The bias voltage can be switched to the gate or the drain of the device under test (DUT) or it can be switched to an external application board on the handler. Eight external relay drives are also provided externally. With a suitable application board, multiple devices can be tested or different capacitance measurements can be done on the DUT.