Possibilities regarding the stabilization of the frequency of millimeter-wave Gunn oscillators

The frequency stability of millimeter-wave oscillators with Gunn diodes as a function of time, and with respect to changes in temperature and supply voltage, can be a vital criterion in connection with the selection of these oscillators for certain applications. An investigation, is, therefore, conducted regarding the approaches which can be employed for the active or passive stabilization of the frequency of millimeter-wave oscillators. Passive frequency stabilization makes use of reflection involving a high-quality resonator to control the oscillator by means of a reaction with a part of the output. Active stabilization is based on an employment of phase-locked loops (PPL). Selection criteria for the phase detector are considered along with the dimensioning of the PPL. A description is provided of the design of the millimeter-wave components of the PPL in planar technology.