| 摘要 |
Provided are, among other things, systems, apparatuses, methods and techniques for converting a continuous-time, continuously variable signal into a sampled and quantized signal. One such apparatus includes an input line for accepting an input signal that is continuous in time and continuously variable, multiple processing branches coupled to the input line, and an adder coupled to outputs of the processing branches. Each of the processing branches includes a continuous-time quantization-noise-shaping circuit, a sampling/quantization circuit coupled to an output of the continuous-time quantization-noise-shaping circuit, a digital bandpass filter coupled to an output of the sampling/quantization circuit, and a line coupling an output of the digital-to-analog converter circuit back into the continuous-time quantization-noise-shaping circuit. A center frequency of the digital bandpass filter in each the 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. |
| 主权项 |
1. An apparatus for quantizing a signal, comprising:
(a) an input line for accepting an input signal; (b) a quantizer having an input and an output; (c) a bandpass quantization-noise-shaping circuit having a first input coupled to the input line, a second input coupled to the output of the quantizer, and an output coupled to the input of the quantizer; and (d) a calibration circuit that includes: a first input coupled to the input line; a second input coupled to the output of the quantizer; a quantization noise estimator having a first input that is coupled to the first input of the calibration circuit, a second input that is coupled to the second input of the calibration circuit, and an output; a quantization element having an input that is coupled to the output of said quantization-noise estimator, and also having an output; a downconverter having an input that is coupled to the output of said quantization element, and also having an output; a level detector having an input which is coupled to the output of said downconverter, and also having an output; and an adaptive control component having an input which is coupled to the output of said level detector an output which is used to control a settable parameter within the bandpass quantization-noise shaping circuit, wherein said quantization noise estimator provides at its output, an error signal comprising a value that is based on a difference between a signal provided to the first input of said quantization noise estimator, and a signal provided to the second input of said quantization noise estimator; wherein said quantization element generates at its output, a quantized version of a signal provided to its input; wherein said downconverter generates at its output, a baseband error signal that results from frequency shifting a signal provided at the input of said downconverter, and wherein said level detector generates an output having a value that comprises a measure of strength of a signal provided at the input of said level detector. |
