Frequency Stable M.I.C. S-Band and C-Band Pulsed Trapatt Oscillators

Microstrip pulsed TRAPATT oscillators using devices designed for S-band have been operated in the fundamental and second harmonic extraction modes to give efficient high power operation at S and C-band frequencies. Conversion efficiencies of greater than 30% in the fundamental mode at 2.5 GHz and 10% in the second harmonic mode at 5 GHz have been achieved. Both planar and mesa device structures have been used to achieve TRAPATT operation at current densities in excess of 10 kA.cm-2 without the problems of premature burn out. A pulse duty cycle of 1000:1 was used. The importance of low loss parasitic diode resistance for efficient operation at high current levels is demonstrated. Finally, a frequency injection locking techniques is employed to overcome the frequency chirp of the free running oscillator and locking gains in excess of 20 dB are reported.