Design of IMPATT-Oscillators in the E- and W-Band

IMPATT-oscillators are often used to generate small and medium RF power in the millimeter wave range (E-band 60-90 GHz, W-band 75-110 GHz). This paper describes the design and the construction of oscillators which are able to provide excellent output power at all frequencies in a complete waveguide band. This is achieved with a single diode by varying the internal structure of the oscillator /1/. Some measurement results of the tuning behaviour of the oscillator depending on the diode current and the parameters of the internal structure are presented as well as the AM-noise and the spectrum of typical 90 GHz oscillators. An investigation of the equivalent circuit of the oscillator is undertaken. The values of the elements of the equivalent circuit are calculated using the formulas specified by Marcuvitz /2/ and Harrington /3/ and are verified by model measurements in the Ka-band. With the results some predictions on how the tuning behaviour of the oscillator depends on the internal structure can be made.