Patent ID: 9547035
Date: 2017-01-17
CPC Classifications: G01R,G11C,H03F,H03K

Claim:
1. A test system for measuring at least one parameter of a device under test (DUT) comprising a transistor, the system comprising: a first voltage source unit configured to supply a gate voltage to a gate of the transistor, the first voltage source unit comprising a voltage measurement device; a second voltage source unit configured to supply one of a drain voltage or a source voltage to a drain or a source of the transistor, respectively, the second voltage source unit comprising a current measurement device configured to detect one of a drain current or a source current flowing through the drain or the source of the transistor, respectively; a feedback unit configured to connect with the current measurement device and to output a feedback current during a feedback control operation, based on the one of the drain current or the source current detected by the current measurement device; and an error amplifier configured to output a feedback control signal, based on comparison of the feedback current and a target current value, to the first voltage source unit, wherein the first voltage source unit is further configured to adjust the gate voltage of the transistor in response to the feedback control signal so that the one of the drain current or the source current converges to match the target current value, and wherein the error amplifier includes a feedback gain determined based on the target current value and a coefficient, which is determined by a relationship between the gate voltage and the one of the drain current or the source current in a sub-threshold region of the transistor.