| 摘要 |
Provided are the following: an operational amplifier that does not detract from speed performance, that is a high-impedance input type, and that can reduce generated noise; and a charge amplifier that uses the operational amplifier. In the present invention, the following are provided: a first buffer (11) and a second buffer (12) that are disposed in parallel and that each have bipolar transistors which are connected so as to be complementary and in which emitters are mutually connected, and that have biasing diodes; a resistor (Re) that, between the buffers, is connected between the connection points between the emitters; a first current-to-voltage conversion circuit (13) and a second current-to-voltage conversion circuit (14) that connect the first and second buffers to a positive electrode power-source line and a negative electrode power-source line; first and second connection-type field effect transistors (Q15, Q25) that control the current flowing in the diodes; and an output stage (15) that is connected to the output of the first and second current-to-voltage conversion circuits. The gate of the first and the gate of the second connection-type field effect transistor serves as an input terminal. |
