Patent ID: 8095094
Filing Date: 2012-01-10
Classification: H03F,H03G

Abstract:
1. A communication device including a transmission oscillator for generating a transmission signal having a predetermined frequency, a first variable gain amplifier for amplifying a signal output by said transmission oscillator, a phase control loop having an amplitude detector and for controlling a phase of the transmission signal output by said transmission oscillator, and an amplitude control loop for controlling a gain of said first variable gain amplifier to control an amplitude of the transmission signal output by said first variable gain amplifier, said communication device executing calibration of said amplitude control loop, comprising: a second variable gain amplifier disposed on a feedback path of said amplitude control loop which feeds back a signal related to an output level of the transmission signal to said amplitude detector; and a third variable gain amplifier disposed on a forward path extending from said amplitude detector to said first variable gain amplifier, wherein upon execution of said calibration, a gain of said second variable gain amplifier is varied in a state where a first value for setting a gain of said first variable gain amplifier is given to said first variable gain amplifier to thereby detect a gain of said second variable gain amplifier at the time when an output of said second variable gain amplifier is equal to a predetermined value, the gain of said second variable gain amplifier is varied in a state where a second value for setting the gain of said first variable gain amplifier is given to said first variable gain amplifier to thereby detect a gain of said second variable gain amplifier at the time when the output of said second variable gain amplifier is equal to a predetermined value and decide a gain of said third variable gain amplifier based on a difference between said detected two gains of said second variable gain amplifier.