Measurement method for microwave device noise characteristics

Noise introduced by microwave device itself has negative influence on signal processing and system performance. Measurements of microwave device noise characteristics, including noise Figure and four noise parameters, are one of the key and most challenging work in radio frequency and microwave engineering. Several kinds of measurement methods have been proposed. Source pull method is a classical way to measure noise characteristics by varying source impedance (or admittance) of device under test (DUT). However, the choice of source impedance affects the measurement accuracy significantly. Unsuitable number (much more than four) and positions of source impedances will increase measurement time, make experiment process more complicated, and introduce more uncertainty factors. To avoid the problems mentioned above, in this paper, the tuner based iterative cold method with only four source impedances is presented to determine noise characteristics of microwave device. A series of experiments on packaged microwave amplifier are performed. Results of the noise figures calculated by measured noise parameters and those directly measured by noise Figure analyzer are compared at different frequencies and show a fair good agreement which verify the efficiency and accuracy of measurement method.