Measurement of the transistor noise parameters using multi-state radiometer system

A new approach to noise characterization of microwave transistors is presented. It employs a novel noise measurement instrument, the multi-state radiometer, capable of simultaneous measuring the noise temperature and the impedance of one-port devices. Its unique measurement potential is achieved thanks to specific noise excitation of the device at the input of an RF total power radiometer. Due to gauging the power of interfering noise waves, its operation is analogous to that of six-ports and multi-state reflectometers, thus resulting in similar techniques of calibration and accuracy enhancement. Generally, the multi-state radiometer is calibrated using several impedance and noise temperature standards and after that can be used for measuring unknown devices at extreme low-power noise stimulus. This capability was utilized to characterize both the noise and small-signal properties of GaAs transistors using the cold-source measurement technique. Experimental results validate the novel noise measurement approach called as the multi-state radiometry.