| 摘要 |
PROBLEM TO BE SOLVED: To expect a stable operation even if power source voltage is lowered and to provide the new form of a front end amplifier which is capable of operat ing by even single power source voltage. SOLUTION: Almost all the photoelectric current ip generated by receiving light by a photo diode (PD) 2 becomes iRF flowing in a feedback resistance RF when incident light intensity is weak, between the source and drains of the FETs 6 connected with the feedback resistance RF in parallel it becomes in a conductive state as incident light intensity is increased, the ip is shunted into iRF and iFET, transimpedance is equivalently lowered and the drop of the output potential by the feedback resistance RF is suppressed. Further, when incident light intensity is increase, a front end amplifier is operated up to larger optical input by flowing gate bias current in the gate of the input stage FET of an amplifier 4 and shunting the photoelectric current ip into iRF, iFET and ig . |
