VOLTAGE LIMIT CIRCUIT, SEMICONDUCTOR INTEGRATED CIRCUIT AND IC CARD

摘要

PROBLEM TO BE SOLVED: To realize a data reception circuit (input circuit), for which power consumption and a power loss are less and by which a high frequency input signal is given to an internal circuit, while its voltage is limited with respect to a transceiver use semiconductor integrated circuit mounted on a contactless IC card employing electromagnetic coupling. SOLUTION: A diode D1 is connected between an emitter of a bipolar transistor(TR) Q1, whose base receives a constant voltage and a terminal T1(T2) receiving an AC signal, so as to prevent a current flowing from the input terminal when the input signal increases more than a prescribed level. Moreover, a level of the signal delivered to an internal circuit for that time is clamped by a base-emitter junction of the bipolar TR Q1.