本发明的侦测器电路使侦测器电路的线性度得以提高。其包括：第1晶体管，该第1晶体管的基极输入有交流信号，并从集极输出与交流信号相对应的第1侦测信号；第2晶体管，该第2晶体管的基极输入有第1侦测信号，并从集极输出与第1侦测信号相对应的第2侦测信号；以及交流信号路径，该交流信号路径向第2晶体管的基极提供交流信号。

Provided is a detector circuit that includes: a first transistor that has an alternating current signal input to a base thereof, and that outputs a first detection signal that depends on the alternating current signal from a collector thereof; a second transistor that has the first detection signal input to a base thereof, and that outputs a second detection signal that depends on the first detection signal from a collector thereof; and an alternating current signal path along which the alternating current signal is supplied to the base of the second transistor.