This letter describes an analysis of the close to carrier phase noise characteristics of the Colpitts oscillator circuit with two or more crystal resonators. The open-loop impedance and the quality factor of a regular oscillation state are computed by using a nonlinear transistor model. Moreover, based on the Leeson’s model, the near carrier phase noises are estimated using the calculated Q-factors. As a result, it was shown by using a crystal filter that the phase noise close to carrier frequencies is improved.

抄録全体を表示

This paper describes an analysis of the close to carrier phase noise characteristics of the Colpitts and Butler oscillator circuits. It is shown that the quality factor can be improved by introducing two or more crystal resonators in the oscillation circuits. Based on the Leeson's model, the near carrier phase noise is estimated using the calculated quality-factor obtained by the analysis of the frequency slope in the output impedance. As a result, it was shown by using plural crystal resonators in the phase noise close to carrier frequencies are improved.

抄録全体を表示

An improved bi-mesa structure optimized for resonator mounting is proposed. To evaluate mounting influences, the frequency differences between clamp and free X-edge conditions are calculated using a two-dimensional finite element method in the X-Y' region. When the outer mesa height was lower than 20% of the thick area, the frequency differences are less than 10% of standard-type bi-mesa resonator values. These results indicate that the improved bi-mesa structure has good separation from the mounting influences.

抄録全体を表示

To improve the temperature characteristics of SC-cut oscillators without degrading their phase noise and short term stabilities, an oscillator circuit has been designed. This circuit uses an AT-cut resonator as a temperature reference of the output frequency, that is, the oscillation frequency of the SC-cut circuit traces the temperature characteristics of the AT-cut resonator. Experimental results show that the frequency stability for the temperature is improved 30 times better than normal oscillators.

抄録全体を表示