| 摘要 |
PROBLEM TO BE SOLVED: To reduce the current consumption in an emitter follower, which is the output circuit of a preamplifier for a photoelectric conversion element, when the input to the photoelectric conversion element is small. SOLUTION: The current of a photoelectric conversion element 11 is amplified by negative feedback amplifiers (14-17). At the same time, a DC current Idc to flow to the photoelectric conversion element 11 is inputted to a current mirror circuit of a mirror ratio (1:α). The output of the current mirror circuit 12 is connected to the emitter of an emitter follower 16, which is an output circuit. An emitter current Ief of the emitter follower 16 becomes (α×Idc). Since the current consumption of the emitter follower 16 is reduced when the input of the photoelectric converting element 11 is small, the power consumption of the preamplifier is decreased. |
