Patent ID: 6337976
Filing Date: 2002-01-08
Classification: H03D,H04B

Abstract:
A selective-calling radio receiver comprising:(a) a PLL frequency synthesizer for generating an initial local signal, said PLL frequency synthesizer comprising a VCO generating said initial local signal and a PLL circuit controlling said initial local signal; (b) an orthogonal converter for orthogonally converting a digitally-modulated received signal to a combination of first and second baseband signals having a phase difference of 90Â° using said initial local signal; said orthogonal converter including: (b-1) a first frequency multiplier for multiplying said initial local signal by a variable multiplication factor to produce a multiplied initial local signal; (b-2) a first phase shifter for producing first and second local signals having a phase difference of 90Â° from said multiplied initial local signal; (b-3) a first frequency mixer for mixing said first local signal with said received signal to produce said first baseband signal; and (b-4) a second frequency mixer for mixing said second local signal with said received signal to produce said second baseband signal; (c) an orthogonal-converter controller for controlling a characteristic of said orthogonal converter according to a frequency band of said received signal; said orthogonal-converter controller controlling said orthogonal converter so as to set said variable multiplication factor of said first frequency multiplier as a desired value and to optimize a characteristic of said first phase shifter according to said frequency band of said received signal; (d) a demodulator for demodulating said first and second baseband signals to produce a demodulated signal; and (e) a decoder for decoding said demodulated signal to derive information transmitted by said received signal, and wherein a set of data for said control signal are stored in a rewritable Read-Only Memory; and wherein said set of data are designed to be read out by a main controller.