Amplifier and radiation detector

An amplifier, comprising:

• a semiconductor substrate;
• an amplifying circuit;
• a feedback capacitor connected in parallel to the amplifying circuit;
• a reset switch integrated on the semiconductor substrate and connected in parallel to the amplifying circuit;
• a first conductive layer directly or indirectly connected to an external bonding wire for signal input;
• a second conductive layer arranged on a side more toward the semiconductor substrate than the first conductive layer;
• and
• a insulating layer interposed between the first conductive layer and the second conductive layer, wherein
• the feedback capacitor is so configured that the insulating layer serves as a dielectric while the first conductive layer and the second conductive layer serve as a pair of electrodes,
• the first conductive layer is connected to an input terminal of the amplifying circuit, and
• the second conductive layer is connected to an output terminal of the amplifying circuit.