CHARGE SENSING AMPLIFIER CIRCUIT FOR COMPENSATING FOR DC LEAKAGE CURRENT, AND X-RAY READOUT INTEGRATED CIRCUIT AND X-RAY SENSOR USING SAME

摘要

A charge sensing circuit according to the present invention includes a photodiode, an operational amplifier, a feedback capacitor, a leakage path transistor for allowing DC leakage current to flow from the photodiode, and a current generating unit for providing drive current. Since a drain and a source are connected between the photodiode and a negative input terminal of the operational amplifier and a power source, and also connected to allow a gate voltage to be determined by the voltage at both ends of a current source transistor where some of the drive current flows and a compensation capacitor, the leakage path transistor may effectively leak a DC leakage current occurring at the photodiode. The current generating unit may stably generate drive current against voltage and temperature variation because it includes a source degeneration resistance.