Direct measurement of FM noise in 80 GHz solid-state oscillators

A technique for the measurement of FM noise in W-band oscillators is described. The method is `direct?, since it makes use of a tuned frequency discriminator operating at the fundamental oscillator frequency. The equipment is compared with other types of noise measurement systems, and the important factors affecting sensitivity are noted. Measurements of the FM noise performance of oscillators utilising GaAs TEOs and Si impatts are presented.