| 摘要 |
PROBLEM TO BE SOLVED: To obtain a preamplifier circuit for light reception with a stably high sensitivity and a broad band circuit by providing a common source amplifier circuit, a source follower circuit and an impedance element or the like. SOLUTION: A common source circuit is configured by a common source amplifier transistor(TR) 2 and an active load 3, a parallel feedback amplifier circuit is configured by the common source circuit, a source follower TR 4 of an output buffer and a feedback resistor 7, and the active load 3 is made up of a FET. Then an input terminal 1 of an amplifier circuit AMP 1 and a gate of the active load 3 are connected by a phase compensation capacitor 8 to compensate a high frequency component of an input signal and to obtain a broad band characteristic. Furthermore, a phase of a high frequency signal to be compensated is changed by connecting an impedance 9 in series with the capacitor 8 to compensate the phase of the amplifier AMP1. Since the phase lag at a high frequency in a negative feedback amplifier circuit is compensated, the amplifier operation is made stable. |
