Abstract

A novel noise measurement method for mixers which exploits mixer noise figure variation with LO power is reported. The method allows for the first time high noise figures, e.g. at the maximum conversion gain point of millimetre wave mixers, to be found. With the technique proposed, noise figures as high as 20 dB can be accurately measured. The suggested method and its advantage over the conventional hot/cold noise measurement are demonstrated for a 65 GHz millimetre-wave GaAs MMIC down converter. For the mixer under test, the measured noise figures obtained were 9.3 dB with 7 dBm LO power and 15.1 dB with 13 dBm LO power, and the respective conversion gains were –1 dB (low noise point) and +3 dB (maximum conversion gain point).