Patent ID: 8803627

Claim:
An apparatus comprising: a phase locked loop (PLL) having a VCO-output high-pass characteristic, the PLL comprising: a voltage controlled oscillator (VCO) having a PLL VCO control input and a modulation VCO control input; and, a phase locked loop controller coupled to the PLL VCO control input and configured to output a PLL control signal to the PLL VCO control input; a signal phase generator configured to generate a phase signal of a desired information-modulated transmit signal; a compensation filter configured to generate a compensated phase signal by increasing low-frequency components of the phase signal to compensate for the VCO-output high-pass characteristic and the VCO gain characteristic; a phase derivative generator having an input coupled to the compensation filter, the phase derivative generator configured to receive the compensated phase signal and to convert the compensated phase signal to a compensated phase derivative modulation signal, and having a modulation control output coupled to the modulation VCO control input for providing the compensated phase derivative modulation signal to the VCO.