A frequency estimation signal generator component arranged to receive an input frequency signal and to generate therefrom a frequency estimation signal. The frequency estimation signal generator component comprises a counter component arranged to sequentially output a sequence of control signal patterns over a plurality of digital control signals under the control of an oscillating signal derived from the received input frequency signal terns. The frequency estimation signal generator further comprises a continuous waveform generator component arranged to receive the plurality of digital control signals and a weighted analogue signal for each of the received digital control signals, and to output a continuous waveform signal comprising a sum of the weighted analogue signals for which the corresponding digital control signals comprise an asserted logical state. The frequency conversion component is arranged to derive the frequency estimation signal from the continuous waveform signal output by the continuous waveform generator component