Patent ID: 6625422
Filing Date: 2003-09-23
Classification: H03B

Abstract:
A signal generator for generating a local oscillation signal for use in a communication apparatus, said generator comprising:an RF signal generator for generating a Radio Frequency (RF) signal in response to a digital signal corresponding to a desired frequency, said RF signal generator comprising: i) a digital synthesizer for generating the digital signal; ii) a digital modulator for outputting one of the digital signal and a modulated digital signal obtained by modulating the digital signal; iii) a D/A converter for converting an output signal of said digital modulator into an analog signal; and iv) a bandpass filter for outputting the RF signal extracted from the analog signal, wherein said digital modulator is switched to output one of the digital signal and the modulated digital signal depending on whether the communication apparatus is receiving a signal or transmitting a signal; a local oscillation signal generator for generating a local oscillation signal; a mixer for mixing the local oscillation signal with the RF signal thereby frequency-converting the signals into a high-frequency signal; and a filter for outputting the high-frequency signal having its out-of-band signal components eliminated therefrom, wherein the output signal of said filter is delivered as the local oscillation signal for use in the communication apparatus.