READOUT CIRCUIT OF DETECTING DEVICE USING CURRENT MIRROR CIRCUIT

摘要

PURPOSE: A readout circuit of a detecting device using current mirror circuit is provided to constantly maintain bias voltage of the detecting device by adapting a unit cell circuit using current mirror circuit to the readout circuit of detecting device. CONSTITUTION: A readout circuit of a detecting device uses a current mirror circuit. The current mirror circuit consists of two NMOSFETs and two PMOSFETs. The PMOSFETs include a first PMOSFET(Mp1) for providing reference current and a second PMOSFET(Mp2) for providing same current as the fist PMOSFET. A gate terminal and a source terminal of the first one are respectively connected with a gate terminal and a source terminal of the second one. In the second one, a drain terminal is connected with the gate terminal. The NMOSFETs include a first NMOSFET(Mn1) for providing reference current and a second NMOSFET(Mn2) for providing same current as the fist NMOSFET. A gate terminal and a source terminal of the first NMOSFET are respectively connected with a gate terminal of the second one and negative terminal of photo-voltage type detecting device. In the second one, a drain terminal is connected with the gate terminal. To the source terminal of the second one is applied same voltage as bias voltage to be applied to the detecting device. The drain terminals of the first/second NMOSFETs are respectively connected with respective drain terminal of the second/first PMOSFETs. A capacitor is connected with the source terminals of the PMOSFETs.