| 摘要 |
PURPOSE: To obtain a compression characteristic having an optional inclination on both logarithmic axes and to obtain characteristics matched with peripheral requests by providing the system with a voltage controlling amplifier in which control voltage is proportional to the logarithmic value of a voltage transmission coefficient, a wave detector and a logarithmic transformer. CONSTITUTION: The input voltage Vi of a signal input terminal 1 is outputted as voltage Vo through the voltage controlling amplifier 2 and sent to the wave detector 3 and an output from the detector 3 is logarithmically transformed by the logarithmic transformer 4 and an output Vc from the transformer 4 controls the amplifier 2. The characteristic of the amplifier 2 is expressed by 1n G=a1 Vc+a0 , provided that G is the gain of the amplifier 2 and Vc is its control voltage. Then, relation between the voltage Vc and the input signal Vi is expressed by 1n Vi=b1 Vc+b0 and b1 , b0 are constants determined by the circuit. When relation between the voltages Vo and Vi is found out by using both the equation, the relation is expressed by the shown equation. When 1 + a1 /b1 is selected as a suitable value in the equation, an I/O characteristic with an optional inclination can be obtained on both the logarithmic axes. |
