| 摘要 |
PURPOSE:To reduce the frequency fluctuation over a wide temperature range for the oscillator circuit in which two crystal oscillators are connected in parallel, by connecting a capacitor in series to one oscillator. CONSTITUTION:Capacitor 15 featuring the characteristics of about 0.3ppm/ deg.C like straight line 11 is connected in series to crystal oscillator 14 which features zero temperature coefficient Tp of about 38 deg.C as well as the frequency temperature characteristics like curve 10. As a result, such frequency temperature characteristics is obtained that Tp rises virtually from 38 deg.C up to 42 deg.C as shown by curve 12. Here, temperature compensating capacitor 15 is connected in series to crystal 14 of the high temperature side and connected in parallel to crystal 13 of the low temperature side respectively. Thus, frequency temperature characteristics 17 of crystal 14 is corrected by capacitor 15, and then frquency temperature characteristics 18 is obtained through virtual rise-up of Tp. Characteristics 18 is then compounded with frequency temperature characteristics 16 of crystal 13 to secure characteristics 19 featuring reduced frequency fluctuation over a wide temperature range. |
