To prevent the amplitude of a correlation peak from being made considerably different by dispersion of a manufacturing step or the like in use for a matched filter.

A transistor 22 is provided as a bias voltage generating means for generating a bias voltage Vig to be applied to the charge injection electrode 17 of a biphase driven type charge coupled device, the transistor 22 is operated in a saturation area, and a voltage Vgs between the gate and source of the transistor 22 is amplified by an operational amplifier 24 as the bias voltage Vig. The transistor 22 is disposed on a chip close to the virtual gate electrode 18a of the transfer electrode 18 of a first phase positioned on the next stage of the charge injection electrode 17 and is produced through the same manufacturing steps with the same gate length as the gate of the virtual gate electrode 18a, thereby having the same threshold voltage and the same transconductance gm as a transistor formed from the virtual gate electrode 18a.