This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

[求助]OPA847作TIA时反相端有一不正常的偏置电压

Other Parts Discussed in Thread: OPA847
 TIA原理图如图所示,仅接上U1部分的电路时,输入的反相端4管脚(即APD1)有一-30mV到-40mV的偏置,正向端3管脚接地。但tia工作似乎正常,输出端电压比输入端高越20mV,sig1后的电路都没有焊接,前面信号源是APD也没有焊接,输入端相当于是悬空的。供电正负5V。看过手册,负向端的失调电压并不是这个量级的,求助!!