Delay circuit

A delay circuit comprising:

• a delay element circuit composed of a plurality of series-connected first circuit elements each being connected to a common power supply line and having a delay time varying correspondingly to a voltage of said common power supply line, said delay element circuit being adapted to receive an input signal and output an output signal obtained by delaying the input signal;
• and
• a phase-locked loop circuit including an oscillator circuit composed of a plurality of series-connected second circuit elements equivalent to said first circuit elements, respectively, and a voltage follower having an input terminal supplied with a voltage signal and an output terminal connected to said common power supply line, said second circuit elements being connected to said common power supply line, said phase-locked loop circuit being adapted to oscillate said oscillator circuit at a predetermined frequency locked to a reference clock frequency by comparing a phase of the reference clock with a phase of an output frequency of said oscillator circuit and controlling the voltage of said common power supply line according to said voltage signal which is generated corresponding to a result of the comparison.