AM-PM synchronization unit

摘要

One embodiment of the present invention relates to a method and apparatus for performing both phase modulation (PM) and amplitude modulation (AM) downstream of a controlled oscillator (e.g., by providing a baseband signal having no phase modulation to a controlled oscillator and performing phase modulation on a high frequency RF signal output from the oscillator), wherein the amplitude modulation is synchronized with the phase modulation. In one particular embodiment, the method and apparatus synchronize modulation of AM and PM signal paths in a manner that provides a polar modulated signal having an amplitude of zero at a symbol boundary (e.g., a transition between different symbols) having a phase of zero (e.g., a phase that crosses through a zero crossing point).

主权项

1. A polar modulation circuit, comprising:
an amplitude conversion component configured to generate a high frequency amplitude modulated signal having a substantially zero amplitude at a switching point time that corresponds to a symbol transition causing a phase discontinuity in a phase modulated baseband signal, and further configured to generate a control signal at the switching point time; and
a phase modulation component configured to receive the control signal and based thereupon to perform a high frequency phase modulation on a high frequency carrier signal at the switching point time, wherein the amplitude conversion component is configured to generate the high frequency amplitude modulated signal by interpolating a plurality of amplitude modulated baseband signal samples to generate a data point having the substantially zero amplitude at the switching point time, wherein the switching point time is temporally located between a first time that a first amplitude modulated baseband signal sample is taken and a second time when a second amplitude modulated baseband signal sample is taken, and wherein the symbol transition comprises a phase shift of 180° in a phase modulated baseband signal occurring between the first and second time.