An apparatus comprising a first circuit and a second circuit. The first circuit may be configured to generate an output signal having a frequency that varies in response to (i) a voltage signal and (ii) a load. The second circuit may be configured to generate the load by coupling one or more resistive...http://www.google.com.hk/patents/US6404294?utm_source=gb-gplus-share專利 US6404294 - Voltage control oscillator (VCO) with automatic gain control
