| 摘要 |
Provided are, among other things, systems, methods and techniques for converting a continuous-time, continuously variable signal into a sampled and quantized signal. According to one implementation, an apparatus includes multiple processing branches, each including: a continuous-time quantization-noise-shaping circuit, a sampling/quantization circuit, and a digital bandpass filter. A combining circuit then combines signals at the processing branch outputs into a final output signal. The continuous-time quantization-noise-shaping circuits include adjustable circuit components for changing their quantization-noise frequency-response minimum, and the digital bandpass filters include adjustable parameters for changing their frequency passbands. |
| 主权项 |
1. 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 having inputs coupled to the input line; and a combining circuit, coupled to outputs of a plurality of said processing branches, that combines signals on said outputs into a final output signal, wherein each of said processing branches includes: (a) a quadrature frequency downconverter, which uses discrete-time cosine and sine sequences to generate in-phase and quadrature outputs at baseband, (b) a first lowpass filter coupled to the in-phase output of the quadrature frequency downconverter, (c) a second lowpass filter coupled to the quadrature output of the quadrature frequency downconverter, and (d) a quadrature frequency upconverter coupled to outputs of the first and second lowpass filters, which uses discrete-time cosine and sine sequences to convert in-phase and quadrature inputs to a higher frequency output, wherein the frequency response of each of said first and second lowpass filters has a magnitude that varies approximately with frequency according to the product of raised sin(x)/x functions, and wherein each of a plurality of said processing branches includes at least one adjustable parameter which, when adjusted, changes at least one of: (i) a frequency of at least one of the cosine or sine sequences, or (ii) a bandwidth of at least one of the first lowpass filter or the second lowpass filter. |
