A polar phase or frequency modulator comprising: - a normalized delay circuit configured to delay edges of an input carrier signal (CLK_IN) based on digital normalized delay control values (φ i) to generate a modulated output signal (RF_OUT); and - a normalized delay calculator configured to receive at a first input the modulated output signal (RF_OUT) and having either: a second input configured to receive phase samples (PHASE) at a rate different to the frequency of the modulated output signal (RF_OUT), each phase sample indicating a target phase offset of the modulated output signal (RF_OUT) with respect to the input carrier signal (CLK_IN); or a third input configured to receive frequency samples (FREQ') at a rate different to the frequency of the modulated output signal (RF_OUT), each frequency sample indicating a phase increment to be applied to the input carrier signal (CLK_IN) and corresponding to a target frequency of the modulated output signal (RF_OUT); or the second input configured to receive the phase samples and the third input configured to receive the frequency samples, the normalized delay calculator being configured to generate the digital normalized delay control values (φ i) based on the phase samples and/or frequency samples, characterized in that the digital normalized delay control values (φ i) are supplied to the normalized delay circuit, at the rate of the modulated output signal (RF_OUT). - a normalized delay circuit configured to delay edges of an input carrier signal (CLK_IN) based on digital normalized delay control values (φ i) to generate a modulated output signal (RF_OUT); and - a normalized delay calculator configured to receive at a first input the modulated output signal (RF_OUT) and having either: a second input configured to receive phase samples (PHASE) at a rate different to the frequency of the modulated output signal (RF_OUT), each phase sample indicating a target phase offset of the modulated output signal (RF_OUT) with respect to the input carrier signal (CLK_IN); or a third input configured to receive frequency samples (FREQ') at a rate different to the frequency of the modulated output signal (RF_OUT), each frequency sample indicating a phase increment to be applied to the input carrier signal (CLK_IN) and corresponding to a target frequency of the modulated output signal (RF_OUT); or the second input configured to receive the phase samples and the third input configured to receive the frequency samples, a second input configured to receive phase samples (PHASE) at a rate different to the frequency of the modulated output signal (RF_OUT), each phase sample indicating a target phase offset of the modulated output signal (RF_OUT) with respect to the input carrier signal (CLK_IN); or a third input configured to receive frequency samples (FREQ') at a rate different to the frequency of the modulated output signal (RF_OUT), each frequency sample indicating a phase increment to be applied to the input carrier signal (CLK_IN) and corresponding to a target frequency of the modulated output signal (RF_OUT); or the second input configured to receive the phase samples and the third input configured to receive the frequency samples,