Bang-bang offset cancellation (autozero)
AssigneeSTMicroelectronics (Canada) Inc.
InventorsJohn Hogeboom, Pat Hogeboom-Nivera
Life of this patent
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Abstract
A receive channel offset correction scheme utilizes “eye edge” samplers and demultiplexers already present and essential for operation of the CDR algorithm, and adds only simple word-rate logic, with no new analog circuitry. The result is the ability to precisely determine the offset polarity as well as to get an approximate immediate measure of the offset magnitude. The offset detected includes all of the analog circuitry in the channel, including the samplers themselves.
Claims20
A non-linear offset regulator loop for a receiver comprising:
- a summer for receiving an analog signal;
- a slicer coupled to an output of the summer;
- a sampler coupled to an output of the slicer;
- a counter coupled an output of the amplifier;
- a logic block coupled to an output of the counter;
- a frequency divider coupled to the counter and the logic block;
- and
- a DAC coupled to the summer and to the logic block.
An offset cancellation method for a receiver comprising:
- counting the balance of zero edge bits versus one edge bits;
- integrating the difference;
- and
- applying an incremental offset correction when the integral reaches a predetermined limit.
A receiver architecture comprising:
- a linear equalizer;
- a plurality of limiting amplifiers coupled to the linear equalizer;
- a plurality of sampling latches coupled to the limiting amplifiers;
- a filter coupled to the sampling latches;
- a data demultiplexer coupled to the filter;
- an auto-zero block coupled to the data demultiplexer;
- and
- an offset compensation DAC coupled between the auto-zero block and the linear equalizer.
Dependencies are inferred from the claim text.