Abstract: A frequency synthesizer includes a controlled oscillator which is responsive to a frequency control input signal, to generate an output frequency. A programmable frequency divider is responsive to the output frequency and to a divider control input, to divide the output frequency by a first integral ratio or by a second integral ratio in response to the divider control input, to thereby produce a divided signal. A phase comparator is responsive to a reference frequency signal and to the divided signal, to compare the reference frequency signal and the divided signal, and thereby produce a first error signal. A sigma-delta modulator is responsive to a modulation input to produce the divider control input. A loop filter is responsive to the first error signal, to thereby produce the frequency control input signal. Ripple compensation signals and direct modulation signals may also be provided, to provide a three-point modulator for a frequency synthesizer. Analog and digital embodiments may also be provided.

Abstract: A secure radio personal communication system and method includes a base station which relays cellular verification signals between a wide area cellular network and a cellular terminal via the wire telephone network. Thus, cellular telephone calls which are routed to a cellular terminal via a base station, when the cellular terminal is within a local region covered by the base station, may be exchanged between the cellular network and cellular terminal over the wire telephone network. Calls from the wide area cellular network which are routed through the base station can thus employ the same security systems and methods which are employed by the wide area cellular network. Signals between the base station and the cellular terminal are preferably exchanged when the cellular terminal is parked in the base station. Verification and encryption signals may be exchanged.

Abstract: A low cost, easily manufactured analog to digital converter uses MOS switching technology easily combined on an integrated circuit with other signal processing circuitry. An input capacitor stores an input analog voltage, and a pumping capacitor is switchably connected to the input capacitor to charge or discharge that input capacitor to a reference value. The number of charge or discharge events is used to generate a digital value for the input analog voltage.

Abstract: A power saving standby mode that can be used in mobile radio stations operating in current networks and improves in the intended message reception. The invention enters the power down mode principally contingent upon the CRC check being successful. Additionally, the invention uses a cumulative majority vote procedure which results in a higher probability of correct reception of a message addressed to the receiving station.