Post-distortion filter for reducing sensitivity to receiver nonlinearities
AssigneePMC-Sierra, Inc.
InventorsMatthew W. McAdam, Anthony Eugene Zortea
Life of this patent
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Abstract
Methods and apparatus for reducing sensitivity to nonlinearities in the receiver of a digital communications system are disclosed. One aspect can be referred to as a Post-Distortion Decision Feedback Equalizer (PDFE). A gain stage is often implemented as a variable gain amplifier (VGA), and can introduce significant nonlinearities, a problem exacerbated by signals with a large peak-to-average ratio (PAR). One embodiment provides feed forward information from the VGA regarding its status to a DFE, and the DFE adjusts its filtering based on the provided information. The advantages are also applicable to fixed-gain amplifiers and to transversal filters.
Claims19
A method of extracting symbols embedded within a received signal, the method comprising:
- amplifying the received signal in real time with an input amplifier to generate an amplified signal, wherein a symbol is embedded within the amplified signal;
- generating an indication of non-linearity of the input amplifier;
- filtering the amplified signal with a filter, wherein a signal processing path of the filter is split into a plurality of separate filtering paths for the same amplified signal including at least a first filtering path with a first set of one or more filter coefficients and a second filtering path with a second set of one or more filter coefficients such that the filter maintains at least two different selectable responses;
- selecting a filter response based on the indication of non-linearity;
- and
- slicing the filtered signal to extract symbols.
A method of extracting symbols embedded within a received signal, the method comprising:
- amplifying the received signal in real time with an amplification process to generate an amplified signal, wherein a symbol is embedded within the amplified signal;
- generating an indication of non-linearity of the amplification process;
- filtering the amplified signal, wherein filter coefficients used for filtering vary at least partially based on the indication of non-linearity and on a determined symbol of a symbol period earlier than that of the symbol being extracted, wherein filtering further comprises:
- filtering using at least two different feedback paths having one or more different filtering coefficients;
- and
- selecting a feedback path based on the indication of non-linearity.
- wherein the at least two different feedback paths comprise at least a first feedback path with at least a first coefficient cH and a second feedback path with at least a second coefficient cL, and wherein selection between at least the first feedback path or the second feedback path changes the filter coefficients used for filtering;
- and
- slicing the filtered signal to extract symbols.
Dependencies are inferred from the claim text.