Patent ID: 6476746
Filing Date: 2002-11-05
Classification: H04B

Abstract:
A cellular base station having a digital input signal at a first speed and an analog output comprising:a digital signal base-band processing modulator for processing and modulating the digital input signal; a high speed digital-to-analog converter coupled to the digital signal base-band processing modulator for converting the digital signal to a converted analog signal at an intermediate frequency, wherein the high speed digital-to-analog converter includes, a storage means having stored outputs of a number of predetermined interpolated samples of a delta-sigma converter corresponding to all possible values of said digital input, said storage means coupled to receive said digital input, a plurality of digital-to-analog converters coupled to said storage means to receive said stored outputs, said plurality of digital-to-analog converters clocked by multi-phase clocks wherein each phase applied to each of said plurality of digital to analog converters is delayed with respect to a next one by an oversampling period equal to the Nyquist period divided by the number of predetermined interpolated samples, and a plurality of digital-to-analog converters coupled to said storage means to receive said stored outputs, said plurality of digital-to-analog converters clocked by multi-phase clocks wherein each phase applied to each of said plurality of digital to analog converters is delayed with respect to a next one by an oversampling period equal to the Nyquist period divided by the number of predetermined interpolated samples, and a summer coupled to said plurality of digital-to-analog converters for summing all output from said plurality of digital-to-analog converters to generate said analog output; a radio frequency modulator coupled to the high speed digital-to-analog converter to receive the converted analog signal and to modulate the signal at a broadcasting frequency, the broadcasting frequency is greater than the intermediate frequency of the signal; and an antenna coupled to receive and transmit the radio frequency signal at the broadcasting frequency.