| 摘要 |
<p>PURPOSE:To widen the dynamic range having desired leading and trailing characteristics, by inputting a signal voltage in logarithmic conversion to an operational amplifier, integrating the output via a P-N junction element, and feeding back the output of integration to an amplifier through resistance division. CONSTITUTION:An input signal at a terminal 11 is logarithmic-converted at an operational amplifier 31 via an absolute circuit 20 and applied to a noninverting input terminal of an operational amplifier 33. The amplified 33 output is applied to an integration capacitor C35 via a diode D34, and output voltage Vc is given to a series circuit consisting of a D41 and a reference current source 42 via an operational amplifier 40, and a logarithmic compression type level detecting output is obtained from a terminal 12. The amplified 40 output is applied to a voltage division circuit 46, and the output is fed back to an inverting input of the amplifier 33. The output of the amplifier 33 is given to a circuit 46 via a compensation diode 43 and an operational amplifier 45. With the constitution like this, the conversion characteristics of the output voltage is independent of the dividing ratio of the circuit 46 and the dynamic range can be extended with desired leading and trailing characteristics.</p> |
