Threshold adjusting circuit of the signal attenuation characteristic

摘要

The circuit includes an asymmetric differential stage which has branches (Q1,Q2) of low and high gain which control respective branches (Q3,Q4) of a symmetrical differential stage. The quiescent current (Ii) of the asymmetric stage corresponds to the output of a signal amplitude suppression portion. The quiescent current (I1) of the symmetrical stage corresponds to the maximum amplitude of a signal supplied by one of its branches. The low and high gain branches are controlled by the input voltage and a voltage (Vb) which corresponds to the voltage at the start of the amplitude suppression portion, respectively.