Level detecting circuit

摘要

A level detecting circuit for producing a level detected output signal in response to an input signal includes a logarithmic converting amplifier which logarithmically converts the input signal into a logarithmically converted signal; a differential error amplifier which produces a logarithmically amplified signal in response to the logarithmically converted signal and at least one feedback signal; an integrating capacitor supplied with the logarithmically amplified signal through a PN junction for producing an integrated signal; a voltage dividing circuit for voltage dividing the integrated signal and the logarithmically amplified signal in accordance with a selected ratio and supplying at least one resultant voltage divided signal as the at least one feedback signal to the differential error amplifier; and an output PN junction for producing the level detected output signal in response to the integrated signal.