INTERFACE CIRCUIT FOR RECORDING A SPEECH VOICE IN A TELEPHONE TERMINAL, PARTICULARLY CONCERNED WITH RECORDING SPEECH CONTENTS OR A TRANSCEIVING RESPONSE MESSAGE BY USING AN EXTERNAL RECORDING DEVICE IN THE TELEPHONE TERMINAL

摘要

PURPOSE: An interface circuit for recording a speech voice in a telephone terminal is provided to output a speech voice signal transmitted or received through a communication line to a recording jack, and to connect a recorder with the recording jack without using a transformer when matching impedance, thereby reducing a mounting space. CONSTITUTION: A differential amplifier(10) differentially amplifies a transmitting voice signal and a receiving voice signal to mix the amplified voice signals, and outputs the mixed voice signals. An inverting amplifier(12) inversely amplifies the mixed voice signals, and outputs the inversely amplified voice signals. A level controller(14) controls levels of the inversely amplified voice signals, and outputs the level controlled voice signals.