Sampling/quantization converters

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 coupled to the input line, each of said processing branches including:
• (a) a continuous-time quantization-noise-shaping circuit, (b) a multi-bit sampling/quantization circuit coupled to an output of the continuous-time quantization-noise-shaping circuit, (c) a nonlinear bit-mapping circuit coupled to an output of the multi-bit sampling/quantization circuit, (d) a digital bandpass filter coupled to an output of the nonlinear bit-mapping circuit, (e) a digital-to-analog converter (DAC) circuit coupled to the output of the multi-bit sampling/quantization circuit, and (f) a line coupling an output of the digital-to-analog converter circuit back into the continuous-time quantization-noise-shaping circuit;
• and
• an adder coupled to outputs of the plurality of processing branches,
• wherein a frequency band selected by the digital bandpass filter in each said processing branch corresponds to a minimum in a quantization noise transfer function for the continuous-time quantization-noise-shaping circuit in the same processing branch, and
• wherein the nonlinear bit-mapping circuit in each of said processing branches performs a scaling operation, on a bit-by-bit basis, that matches imperfections in a binary scaling response of the digital-to-analog converter in the same processing branch.