| 摘要 |
Rapid frequency synthesizer apparatus, particularly for use in high speed frequency hooping systems, includes a voltage controlled oscillator (VCO) and a memory in which are stored digital control voltage commands corresponding to the various frequencies to be synthesized by the VCO. A controller, responsive to channel selection commands, addresses the memory and causes the corresponding digital control voltage command to be generated. A digital-to-analog converter receives the digital control voltage command and converts it to an analog control voltage signal which is fed to the VCO. The resulting VCO output signal, at frequency, fout, is compared in a frequency counter with a reference frequency fR. The controller controls operation of the frequency counter so that a difference between the actual synthesized frequency and the programmed frequency is determined. Responsive to this difference, the controller causes the addressed control voltage command to be modified in a manner designed to reduce the difference the next time the same programmed frequency is selected. A corresponding method for providing rapid frequency synthesis is described. |
