Patent ID: 8264390

Claim:
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 plurality of processing branches coupled to the input line, 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-continuously-variable signal converter; and an adder coupled to an output of the analog bandpass filter in each of the processing branches, 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, and wherein each of the discrete-time noise-shaping/quantization circuits has a conversion-noise frequency-response minimum that corresponds to a frequency band selected by the analog bandpass filter in the same processing branch.