| 摘要 |
PURPOSE:To produce a conversion table with high efficinecy, by connecting an automaticvoltage control circuit to a PLL circuit of a frequency synthesizer. CONSTITUTION:First a P-ROM7 and a D/A converter 8 are separated from each other by a switch 11. When digital values D1-Dn, i.e., the channel information are supplied to a programable counter 6, the control voltage VC of a VCO5 varies by the function of a PLL circuit. The voltage VC is applied to the minus (-) input of a comparator 10 via a time constant circuit 9. The comparator 10 applies the voltage corresponding to the error between the voltage VC and the reference voltage VR to a preset input 52 via a switch 11. The voltage of the input 52 differs by the values D1-Dn. Accordingly, the voltage of the input 52 receives an A/D conversion through an A/D converter 12 every time the values D1-Dn have some difference and then writtn into the P-ROM packaged to a P-ROM writer 13. In this case, the values D1-Dn function as the address signals. |
