Abstract: A reduced phase noise multiplication, digitally controlled frequency synthesizer employs a subsampling digitizer to downconvert (perform ‘constructive aliasing’ of) the synthesizer's output frequency to baseband for precision tuning of the synthesizer's output frequency in a digitally controlled phase locked loop. The use of a digitally controlled phase locked loop allows the stepsize of the synthesizer output frequency to be controlled in very small (e.g., sub-Hertz) increments. Since the phase locked loop uses all digital components for tuning control, no additional frequency division by the loop is required. This means that only the value of the subharmonic ratio ‘n’ of the subsampling clock to the analog-to-digital converter will determine multiplicative phase noise error.

Abstract: A reduced phase noise multiplication, digitally controlled frequency synthesizer employs a subsampling digitizer to downconvert (perform ‘constructive aliasing’ of) the synthesizer's output frequency to baseband for precision tuning of the synthesizer's output frequency in a digitally controlled phase locked loop. The use of a digitally controlled phase locked loop allows the stepsize of the synthesizer output frequency to be controlled in very small (e.g., sub-Hertz) increments. Since the phase locked loop uses all digital components for tuning control, no additional frequency division by the loop is required. This means that only the value of the subharmonic ratio ‘n’ of the subsampling clock to the analog-to-digital converter will determine multiplicative phase noise error.

Abstract: The calibration method preferably comprises the steps of: driving the analog-to-digital converter (ADC) with at least one test signal; calibrating the driven ADC over a series of successive ADC calibrations; generating a series of successive ADC figure of merit measurements for respective successive ADC calibrations, the series of successive ADC figure of merit measurements defining at least a portion of a curve having a local minimum/maximum; and stopping calibrating at an ADC calibration corresponding to the local minimum/maximum of the curve defined by the series of successive ADC figure of merit measurements. The step of calibrating preferably comprises incrementally calibrating the ADC over the series of successive ADC calibrations. The method preferably further comprises the step of determining the local minimum/maximum of the curve.