Wideband direct modulation with two-point injection in digital phase locked loops

摘要

A digitally controlled oscillator (DCO) modulation apparatus and method provides a wideband phase-modulated signal output. An exemplary modulator circuit uses an oscillator in a phase-locked loop. The circuit receives a wrapped-phase input signal, unwraps the wrapped-phase input signal to generate an unwrapped-phase signal, and differentiates the unwrapped-phase signal. The wrapped-phase input signal and the differentiated unwrapped-phase signal are both injected into a feedback loop of the modulator circuit. The feedback loop may include a multi-modulus frequency divider with a frequency divisor that is temporarily incremented or decremented to cancel out abrupt phase jumps associated with the wrapped-phase to unwrapped-phase conversion.

主权项

1. A circuit comprising:
a phase-locked loop having a controllable oscillator with an oscillator output and a control signal input, the oscillator output and control signal input being connected through a feedback loop; a wrapped-phase input for receiving a wrapped-phase input signal; a first adder operative to inject the wrapped-phase input signal into the feedback loop; unwrapped differentiation logic operative to generate a differentiated unwrapped-phase signal from the wrapped-phase input signal; and a second adder operative to inject the differentiated unwrapped-phase signal into the feedback loop.