Fast risetime InP oscillators employing cavity stabilisation and pulsed priming techniques

Abstract: A high-peak-power short-pulse-length J-band (10-20 GHz) oscillator using high-efficiency InP devices is described. The circuit techniques employed enable simultaneous satisfaction of the conflicting requirements of a well defined fast RF risetime and extremely good frequency stability during the pulse. Incoherent phase-priming and cavity stabilisation techniques are described. A theoretical treatment is given on the problem of cavity stabilisation techniques for chirp suppression in pulsed oscillators using resonant structures coupled into the output transmission line. For a given pulse length, there exists an optimum value of cavity Q-factor to obtain maximum chirp reduction for minimum insertion loss. The design of this cavity is discussed in detail and some implications on device design and processing techniques to minimise transient thermal impedance are outlined.