SP/LP MODE DETECTION CIRCUIT

摘要

The SP/LP discrimination circuit having a gain control/amplifying means gain controlling and amplifying input signals; an envelope detecting means detecting an envelope of output signal from gain control/amplifying means; a basic level generating means generating a basic level by using the output signal of the envelope detecting means; a comparing means comparing the output signal of envelope detecting means and the basic level; and a mode discriminating means discriminating SP mode or LP mode according to duty ratio of the output signal of the comparing means is disclosed. Thereby, it is possible to simplify the circuit structure comparing to a prior circuit.