SEMICONDUCTOR INTEGRATED CIRCUIT FOR MODULATION AND INSPECTION METHOD FOR OSCILLATION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To realize an LC oscillation type VCO circuit with less frequency shift and to provide a frequency hopping system wireless communication system employing the VCO circuit. SOLUTION: The semiconductor integrated circuit for modulation adopting a frequency hopping system that directly controls the LC oscillation type VCO (134) on the basis of transmission data and selects a carrier frequency to transmit data is provided with a current adjustment circuit (142) that changes a current of a digital/analog converter (132) generating a control voltage for the VCO depending on the carrier frequency so that a deviation in a modulation side control input voltage (Vcont2) indicates a characteristics reverse to a modulation frequency shift characteristics thereby eliminating the shift of the modulation frequency in the VCO.