Patent ID: 9654128
Date: 2017-05-16
CPC Classifications: H03M

Claim:
1. An apparatus for converting a continuous-time, continuously variable signal into a sampled and quantized signal, comprising: an input line for accepting an input signal that is continuous in time and continuously variable; a plurality of processing branches having inputs coupled to the input line, each of said processing branches including: (a) a bandpass noise-shaping circuit, (b) a sampling/quantization circuit coupled to an output of the bandpass noise-shaping circuit, and (c) a digital bandpass filter coupled to an output of the sampling/quantization circuit; and a combining circuit, coupled to outputs of a plurality of said processing branches, that combines signals on said outputs into a final output signal, wherein each of said digital bandpass filters includes: (a) a quadrature frequency downconverter, which uses discrete-time cosine and sine sequences to generate in-phase and quadrature outputs at baseband, (b) a first lowpass filter coupled to the in-phase output of the quadrature frequency downconverter, (c) a second lowpass filter coupled to the quadrature output of the quadrature frequency downconverter, and (d) a quadrature frequency upconverter coupled to outputs of the first and second moving-average filters, which uses discrete-time cosine and sine sequences to convert in-phase and quadrature inputs to a higher frequency output, wherein a center frequency of the digital bandpass filter in each said processing branch corresponds to a stopband region in a quantization noise transfer function for the bandpass noise-shaping circuit in the same processing branch, wherein the frequency response of each of said first and second lowpass filters has a magnitude that varies approximately with frequency according to the product of raised sin(x)/x functions, and wherein each of a plurality of said processing branches includes at least one adjustable parameter which, when adjusted, changes at least one of: (i) a frequency of at least one of the cosine or sine sequences, or (ii) a bandwidth of at least one of the first lowpass filter or the second lowpass filter.