| 摘要 |
PURPOSE:To attain purely a differential offset by utilizing a signal being a difference of maximum values between a non-inverting output and an inverting output and correcting an offset voltage to eliminate the effect of a common mode signal including a DC voltage at the output side. CONSTITUTION:The non-inverting output signal 112 and the inverting output signal 113 are expressed respectively as VP=VPO+(Avi/2) and VN=VNO-(Avi/2), and in equations, where A is a differential gain of the amplifier, vi is an input signal voltage and VPO, VNO are respectively DC components. An output VP' of an amplitude detecting circuit 102 is expressed as VP'=VPO+(Avi'/2), where vi' is the maximum value of the input signal and an output VN' of a detecting circuit 103 is expressed as VN'=VNO. An output voltage VC of a difference circuit 106 via an adder circuit 104 is expressed as VC=VPO+VNO+(Avi'/2)- VT, where VT is a reference voltage. Since the sum VPO+VNO is constant, when the relation of VPO+VNO-VT=-(Avt'/2) is set where vt' is a reference voltage vt' converted into the input as the definition, the VC becomes as VC=A(vi'-vt')/ 2 and the effect of the DC offset voltage is not given onto an output voltage of the difference circuit. |
