Zvi Galani

Analysis and Design of a Single-Resonator GaAs FET Oscillator with Noise Degeneration

This paper presents an analysis of a low-noise dielectric resonator GaAs FET oscillator in a frequency-locked loop (FLL), which is used for FM noise degeneration. In this circuit, one resonator serves both as the frequency-determining element of the oscillator and as the dispersive element of the discriminator. The results of the analysis are used to generate design guidelines. These guidelines were followed in an experimental realization of an X-band circuit. The measured FM noise was--120 and--142 dBc/Hz at 10- and 100-kHz offset frequencies, respectively, and corresponded closely to predicted results.

An overview of frequency synthesizers for radars

The authors present an overview of frequency synthesizer techniques suitable for radar systems. Various synthesizer architectures and key synthesizer components are considered along with a discussion of advantages and disadvantages. Some architectures are hardware intensive and, because of their physical size, are more suitable for stationary or shipboard radars. Architectures requiring smaller volume are more suitable for airborne applications. Direct, phase-locked, and frequency-locked architectures are covered, including key building blocks and performance limitations. The direct digital synthesizer (DDS) architecture is considered briefly, as it is not yet widely used in radar systems. Finally, projections are made of advances in components that have a direct effect on frequency synthesis. >

A Single-Resonator GaAs FET Oscillator with Noise Degeneration

A low noise GaAs FET oscillator circuit is presented. It uses a single dielectric resonator both in the oscillator feedback circuit and as the dispersive element of a discriminator in a frequency locked loop used for noise degeneration. An FM noise level of -120 dBc/Hz at 10 kHz offset was measured at X-band.

A Low Noise Frequency Agile X-Band Source

A low noise frequency agile X-band source designed for a missile seeker Master Oscillator is presented. The source consists of a push-push X-band VCO phase-locked to a single crystal oscillator using a sampling phase detector. The performance of the source is presented under static conditions and the severe missile vibration environment.

The differential reference frequency synthesizer

Indirect digital frequency synthesizers cannot achieve fast frequency switching with closely spaced frequencies because of limitations imposed by the requisite narrow loop bandwidth. A novel dual-loop digital frequency synthesizer is presented which satisfies these conflicting requirements and, in most cases, exhibits improved phase noise performance. Two realizations of the novel frequency synthesizer are presented and compared to a conventional dual-loop digital synthesizer using an example. From this example, it is evident that the use of the differential reference frequency synthesizer allows synthesis of closely spaced frequencies with phase-locked loops that use arbitrarily high reference frequencies and, therefore, can have considerably wider bandwidths and commensurately shorter frequency switching times than can be achieved with conventional dual-loop synthesizers.<<ETX>>