A phase-shifter circuit arranged to receive a reference timing signal and to output a phase-shifted form of the reference timing signal. The phase-shifter circuit comprises a delay circuit arranged to receive the reference timing signal and a delay control signal, and to delay transitions within the reference timing signal to generate the phase-shifted form of the reference timing signal, wherein the amount of delay applied by the delay circuit to the transitions within the reference timing signal is controllable by the delay control signal. The phase-shifter circuit further comprises a delay control circuit arranged to receive a re-timed signal comprising transitions re-timed to transitions of the phase-shifted form of the reference timing signal output by the phase-shifter circuit, and to generate the delay control signal for the delay circuit based on the received re-timed signal.

A frequency divider circuit (200) includes a frequency sub-divider (201) to provide a frequency divided clock, a delay circuit (250) configured to delay the frequency divided clock by N+0.5 cycles of the input clock to generate a delayed clock, and an output circuit (202) configured to generate an output clock based on the frequency divided clock and the delayed clock, where the output clock has a frequency that is equal to 1/(N+0.5) times a frequency of the input clock, and N is an integer greater than one.

A synthesizer module arranged to generate a timing signal. The synthesizer module comprises an odd-numbered frequency divider circuit arranged to receive a reference timing signal and to output at least one frequency-divided signal having a frequency equal to 1/M times the frequency of the reference timing signal, where M is an odd-numbered integer. A 90 phase-shift component is arranged to receive the reference timing signal and to output a 90 phase-shifted form of the reference timing signal. A re-timing circuit is arranged to re-time a set of transitions of the frequency-divided signal to be temporally aligned to transitions of the 90 phase-shifted form of the reference timing signal to generate the timing signal comprising the re-timed transitions of the frequency-divided signal.