Communication semiconductor integrated circuit

摘要

The present invention provides a communication semiconductor integrated circuit wherein a first control voltage for a voltage-controlled oscillator circuit is controlled based on a feedback signal sent from a PLL loop to generate a carrier frequency signal used as a carrier, and under the generation of the carrier frequency signal, a second control voltage for the voltage-controlled oscillator circuit is controlled based on the output of a DA converter circuit for DA-converting a code generated based on transmit data to thereby frequency-modulate an oscillation signal. The communication semiconductor integrated circuit is provided with a frequency adjustment/control circuit which measures the frequency of an oscillation output of the voltage-controlled oscillator circuit and adjusts a reference current value of the DA converter circuit according to the difference between the measured value and a target value to thereby correct the frequency.