Анализ и разработка высокоточного генератора частоты w-диапазона с низким уровнем паразитных гармоник

Abstract

For millimeter waves applications in the W-band 93.5-95.5 GHz, improved frequency synthesizers are highly demanded. Improved frequency synthesizer should be tunable synthesizer with high step resolution and possess high phase noise performance, low spurious harmonic levels and short locking time. These parameters are conflicting parameters in developing a high precision frequency oscillator with a pure spectrum. Therefore, it's necessary to make a compromisation between them. In this paper we present a frequency synthesizer based on a Gunn diode, two stable finely tuned frequency sources, a phase locked loop, and a 10th order subharmonic mixer in the feedback loop is built. The phase noise, spurious levels, and tuning step size of the phase locked loop generator are then analyzed, and the effect of each parameter on the others is introduced. To test the performance of the proposed frequency synthesizer using a spectrum analyzer, the output spectrum of the intermediate frequency was measured on a subharmonic mixer, which corresponds to the spectrum of a phase-locked loop generator. The results show that the proposed phase-locked loop generator can be tuned in steps of less than 1 Hz, and the first two spurious harmonics are far from the fundamental harmonic. These results can be used for designing an enhanced high precision frequency synthesizer with a low level of spurious harmonics and high phase noise performance in millimeter waves applications such as CW RADAR.