Noise suppression circuit for use with FM receiver
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorYasuo Iwamoto
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Abstract
Two semiconductor diodes are serially interconnected across a ratio detector in the same polarity. When the detected output from the ratio detector reaches a predetermined magnitude, both diodes are conducting and the detected output is taken from the junction of the diodes. When the detected output from the ratio detector falls due to a lower received signal level, an increase in noise level is ordinarily experienced. Because the output of the ratio detector is lower, the diodes are no longer fully conductive. This causes an increase in output impedance and a corresponding reduction in noise output.
Claims6
A noise suppression circuit for use with an FM receiver comprising a ratio detector, a series combination formed of a plurality of semiconductor rectifier elements interconnected with the same polarity and having a central junction, each of said semiconductor rectifier elements having nonlinear forward characteristics, said series combination being connected to said ratio detector in a forward direction relative to the detected DC output therefrom to form a DC load circuit for the latter, and means for taking an audio signal from said central junction of said series combination, whereby said semiconductor rectifier elements become conducting when said detected DC output from said ratio detector exceeds a predetermined level thereby providing an audio signal from said central junction.
Dependencies are inferred from the claim text.