| 摘要 |
PURPOSE:To secure the steady conversion even to the narrow pulse input, by constituting the logarithm converting circuit in combination of the operational amplifier and the logarithm converter and then preventing the exponential function type reduction of the discharge voltage fromn being affected by the temperature change. CONSTITUTION:DC input ViN proportional to the value to be obtained is applied to DC input terminal 1. On the other hand, the sampling pulse featuring the fixed duration is supplied to sampling pulse input terminal 2. Then linear gate 3 is opened by the rise of the sampling pulse, and the voltage proportional to input Vin is applied to RC circuit 4 to charge capacitor C of circuit 4. And gate 3 is closed at the fall moment of the sampling pulse to start the discharge of the charged voltage. At the same time, both the saw-tooth wave from saw-tooth wave generating circuit 5 and the voltage sent from circuit 4 and changing in the logarithmic way are applied to adder circuit 6 for addition, and then the voltage showing the exponential function type reduction which is free from any effect of the temperature change is delivered via minimum value detecting circuit 7. |
