Patent ID: 6639933
Filing Date: 2003-10-28
Classification: H03L,H04B

Abstract:
A radio communication apparatus comprising:an antenna; a transmitter having an output; a receiver having an input; and a duplexer which selectively couples either of the input of the receiver and the output of the transmitter to the antenna; wherein the transmitter includes: a phase-locked loop circuit which receives a first signal having a frequency and converts the first signal into an output signal having a transmission frequency; and an output amplifier which amplifies the output signal of the phase-locked loop circuit to produce an output signal of the transmitter and supplies the output signal of the transmitter to the output of the transmitter; and wherein the phase-locked loop circuit includes: a current output type phase comparator which converts a phase difference between the first signal and a second signal into a current signal; a low pass filter which filters the current signal of the current output type phase comparator to produce an output signal; and a current source which supplies a current to an input of the low pass filter.