| 摘要 |
PURPOSE:To attain amplification of a signal with less distortion by utilizing most effectively a straight line part in a transfer characteristic of a differential amplifier circuit in amplifying a monopolar signal. CONSTITUTION:A voltage VI superimposed with a signal voltage is applied to a non-inverting input terminal 305 of a directly coupled differential amplifier 301. Output terminals 307, 308 of the differential amplifier 301 are connected to amplitude detecting circuits 302, 303 and maximum values VP', VN' are detected respectively. A difference circuit 304 takes a difference of outputs of the amplitude detecting circuits 302, 303, amplifies the difference properly and applies an output DELTAVP to an inverting input terminal 36 of the differential amplifier 301. When the gain of the differential amplifier circuit 301 is denoted as A and the gain of the difference circuit 304 as beta respectively, then the relation of DELTAVP= beta(VP'-VN') and VP0-VNO=A(VIO-VR-DELTAVP) is established, a differential offset voltage VOS at the output side is obtained as VOS=VPO'-VNO'=A(VIO- VR)/(1+betaA)-vp', and since the vp' is given as vp'=Avi'/2, the relation of VOS=-Avi'/2 is obtained when Abeta and beta are sufficiently large, and further, an offset voltage VIS at the input side is obtained also as VIS=(VPO-VNO)/A- (vi'/2). |
