COMPARING TWO TYPES OF VHF LOW-NOISE FREQUENCY SOURCES FOR MICROWAVE AND HIGHER FREQUENCY SYNTHESIS

摘要

The Butler and modified Butler-type crystal oscillator circuits have been selected as the candidates to develop low-noise 100 MHz VHF crystal oscillators using SC-cut crystals. A low-noise buffer amplifier with a matching circuit to the 50-ohm output load is commonly used for these two design models. Evaluations of the phase noise performance have been achieved by comparing predicted performance and experimental results for the phase noise performance of each of the two types. The Butler-type phase noise is shown to be less than -162 dBc/Hz in actual results compared with the predicted value of-170 dBc/Hz at a 10 kHz Fourier frequency. The modified Butler-type shows less than -171 dBc/Hz in actual results, compared with the predicted value of -178 dBc/Hz at the same Fourier frequency.