An XOR phase detector for a phase-locked loop PLL comprises an XOR gate which has an input for a periodic reference signal and another input connected to a frequency divider of the PLL. A level shifter has a level shifter input connected to an output of the XOR gate and a level shifter output connectable to a voltage-controlled oscillator VCO of the PLL. The level shifter is connectable between low and high voltage providers and has a high level and a low level. The level shifter is arranged to deliver at its output the high level or the low level depending on whether the voltage at the output of the XOR phase detector is low or high. The level shifter further has a setpoint input for setting the high level to a setpoint level.