Semiconductor integrated circuit for communication and portable communication terminal

Abstract

The present invention provides a semiconductor integrated circuit for communication (radio frequency IC) capable of detecting and correcting variations in an amplitude loop band of a transmission circuit having a phase control loop and an amplitude control loop without using an external measuring apparatus. In a semiconductor integrated circuit for communication (radio frequency IC) including a transmission circuit having a phase control loop for controlling the phase of a carrier wave and an amplitude control loop for controlling the amplitude of a transmission output signal, a calibration circuit for detecting variations in a loop gain of the amplitude control loop and correcting the loop band is provided. The calibration circuit detects variations in a loop gain by comparing a feedback signal with an output signal of a modulation circuit while changing electric parameters of any of circuits on the amplitude control loop step by step, and corrects the loop band by changing characteristics of any of the circuits on the amplitude control loop in accordance with the detected variations.

Dependencies are inferred from the claim text.