Conversion of a discrete-time quantized signal into a continuous-time, continuously variable signal

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 Igin an output;
• a plurality of processing branches coupled to the output of the digital pre-distortion linearizing filter, each of said processing branches including:
• (a) a quantization circuit, (b) a multi-bit-to-variable-level signal converter coupled to an output of the 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 analog bandpass filters in different ones of said processing branches select different frequency bands, and
• wherein the digital pre-distortion linearizing filter has a transfer function that produces an at least approximately all-pass response when convolved with a composite transfer function that represents the combined transfer functions of the analog bandpass filters in the processing branches.