A pulsed IMPATT oscillator at 90 GHz with chirp compensation

Pulsed IMPATT oscillators are key components of many millimeter-wave radar systems. Advantages of these oscillators are related to small size, low weight, and less exacting requirements regarding the employed voltage. The oscillators are, therefore, frequently used as transmitters in radar systems and in systems for communication over short distances. A description is presented of the design of a 90 GHz IMPATT pulsed oscillator and the power supply which provides the current pulses. The design of the current source makes it possible to modify the pulse form. Such a modification can be used to control frequency chirps which are inevitable, when pulsed semiconductor oscillators are employed. The characteristics of the current source and its performance are discussed, and the effects of chirp compensation on the frequency behavior of the oscillator are considered. A frequency chirp near 50 MHz was observed for a pulse output power of 10 W at 90 GHz.