| 摘要 |
A first amplifier 11 amplifies an input signal, and differential-outputs the amplified result in the form of positive-phase output and negative-phase output. A first and second peak detecting parts 12 and 13 are respectively detect and store peak values of the positive-phase output and the negative-phase output of the first differential amplifier 11. The second differential amplifier 14 amplifies a difference between an output of the first peak detecting part 12 and an output of the second peak detecting part 13, and then differential-outputs the amplified result in the form of positive-phase output and negative-phase output. The positive-phase output of the second differential amplifier 14 coincides with a center value of the positive-phase output of the first amplifier 11. The negative-phase output of the second differential amplifier 14 coincides with a center value of the negative-phase output of the first amplifier 11. A combined differential amplifier 15 is provided with a function of amplifying a difference ä(VS1 - VR1) - (VS2 - VR2)ü between a difference (VS1 - VR1) of a first input signal (VS1) and a first reference signal (VR1) and a difference (VS2 -VR2) of a second input signal (VS2) and a second reference signal (VR2). The first input signal is assigned the positive-phase output of the first amplifier 11, the first reference signal is assigned the positive-phase output of the second differential amplifier 14, the second input signal is assigned the negative-phase output of the first differential amplifier 11, and the second reference signal is assigned the negative-phase output of the second differential amplifier 14, respectively. Preferably, an output value of the first differential amplifier 11 receiving no signal input and an output value of the second differential amplifier 14 receiving no signal input are set to be equal. <IMAGE> |
