Patent ID: 8964817
Filing Date: 2015-02-24
Classification: G06T,H04B

Abstract:
1. A frequency converter comprising: an original digital signal generator for generating an original digital signal by digitally converting a first analog signal at a first frequency; an oversampler for oversampling the original digital signal at a second frequency higher than the first frequency; a zero interpolator for generating a plurality of image digital signals by interpolating a data point after the oversampling; a frequency axis image selector for selecting an image digital signal occupying a specific frequency band out of the plurality of image digital signals; and a digital-analog converter for performing noise elimination and waveform shaping for the selected image digital signal occupying a specific frequency band, converting to a second analog signal, and outputting the second analog signal; wherein the digital-analog converter comprises a delta-sigma modulator; wherein the delta-sigma modulator is composed of a non-delay circuit and a delay circuit that are multistage cascaded alternatively to each other via a compositor; wherein an input signal to each of the multistage compositors is weighted and feed-forward added via a constant multiplication circuit and an output signal thereto is weighted and feedback subtracted via another constant multiplication circuit; wherein an output of the delay circuit at the last cascade stage is quantized via a comparator that is a quantizer; and wherein a route consisting of the non-delay circuit, the compositor, and the delay circuit has a digital circuit block where a weighting local feedback loop is formed.