| 摘要 |
PURPOSE:To improve a circuit characteristic in a small scale by a start setting voltage level for compression and expansion with each other after applying a logarithmic transformation to the held peak value of an input signal and then setting an attenuation rate of an attenuator based on the difference between both voltage levels. CONSTITUTION:The output of a peak holding circuit 10 which holds the peak value of an input signal is inputted to a comparing circuit 20 and a differential amplifying circuit 30 respectively after undergoing the logarithmic transformation through a logarithm transformation circuit 11. The circuit 20 and 30 input in parallel the expansion and compression start setting voltage levels V1 and V2. Then the circuit 20 inputs the output of the circuit 11 and the comparing result of both levels V1 and V2 to a switch circuit 12. The circuit 30 inputs the output of the circuit 11 and the difference between both levels V1 and V2 to the circuit 12 respectively. Then the circuit 12 selects the output or the earth potential of the circuit 30 based on the output of the circuit 20 and sets the attenuation rate of an attenuator 13 which inputs the input signal. In such a configuration, the circuit characteristic is improved in a small scale. |
