| 摘要 |
Tuning elements are mounted on a coplanar waveguide probe adapted to be used for on-wafer microwave noise measurement of integrated circuit devices. Each of the tuning elements is a capacitive varactor which is connected between a respective position on the input signal line of the probe and a respective capacitor to ground for the injection of bias voltage. The input signal line carries a gate voltage for the wafer device under test, and the differential voltage between the gate voltage and the bias voltage applied to the respective varactor determines the capacitance presented to the signal line by the varactor. The impedance of the signal line at the point where the probe contacts the wafer can be varied by adjusting the bias voltages applied to the varactors. The position at which each of the varactors is connected to the input signal line depends upon the wavelength of the input signal and is normally less than two wavelengths of the input signal from the end of the probe that contacts the wafer.
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