Patent ID: 9509331
Filing Date: 2016-11-29
CPC Classification: H03M,H04L

Claim Text:
1. An apparatus for converting a discrete-time quantized signal into a continuous-time, continuously variable signal, comprising: an input line for accepting an input signal that is discrete in time and in value; a digital pre-distortion linearizing filter having an input coupled to the input line and an output; a plurality of processing branches having inputs coupled to the output of the digital pre-distortion linearizing filter, and each of said processing branches including: (a) a discrete-time noise-shaping/quantization circuit, (b) a multi-bit-to-variable-level signal converter coupled to an output of the discrete-time noise-shaping/quantization circuit, and (c) an analog bandpass filter coupled to an output of the multi-bit-to-variable-level signal converter; and an adder coupled to an output of the analog bandpass filter in each of the processing branches, wherein each processing branch converts a portion of the input signal spectrum, wherein the discrete-time noise-shaping/quantization circuits in different ones of the plurality of processing branches have conversion-noise frequency-response minima at different frequencies, wherein a frequency response of each of the discrete-time noise-shaping/quantization circuits has minimum conversion noise in a region that corresponds to a frequency band selected by the analog bandpass filter in the same processing branch, and wherein the digital pre-distortion linearizing filter has a transfer function that compensates for at least one of a phase distortion or an amplitude distortion introduced by a filter bank formed by the analog bandpass filters.