| 摘要 |
PURPOSE:To eliminate the need for adjustment by providing a means detecting an output offset and a means subtracting its output from a signal subject to nonlinear compression and inputting its difference signal to a nonlinear expansion circuit so as to allow any distortion to hardly take place even with mismatching in transistors(TRs). CONSTITUTION:TRs 13, 14 and an operational amplifier 17 form a nonlinear compression circuit and TRs 18, 19 and a current mirror circuit 21 form a nonlinear expansion circuit. Moreover, an offset detection transconductance amplifier 23 and a smoothing capacitor 22 smoothing an output of the amplifier and feeding back the result to the base of the TR 19 are provided. Then if the compression characteristic is deviated, the offset is detected to deviate the expansion thereby decreasing the distortion and if the expansion characteristic has a deviation, the output offset is detected and the expansion characteristic is deviated to eliminate the deviation of the expansion characteristic so as to make automatic adjustment the overall input/output characteristic approach an ideal value.
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