Analog N-tap FIR receiver equalizer
AssigneeThe Board of Trustees of the Leland Stanford Junior University
InventorRamin Farjad-Rad
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Abstract
An equalizer includes plural samplers for sampling an incoming input data stream according to plural phases of a sampling clock, each sampler producing a data sample. Operating in the analog domain, a multi-tap finite impulse response (FIR) filter weights the data samples and combines the weighted data samples to produce a filtered data bit. The filtered data bits thus form an equalized output data stream. The equalizer can compensate for characteristics of a communications channel, such as low-pass characteristics. The channel may carry high-speed, e.g., multi-gigabit per second, traffic.
Claims18
A receiver equalizer, comprising:
- samplers for sampling an incoming input data stream according to plural phases of a sampling clock, each sampler producing a data sample;
- and
- a multi-tap finite impulse response (FIR) filter which, in an analog domain, for each data sample, weights said data sample and at least one previous data sample, and combines said weighted data samples to produce an equalized data bit.
A method for equalizing an incoming input data stream, comprising:
- sampling the input data stream according to plural phases of a sampling clock to produce data samples;
- and
- filtering the data samples with an analog multi-tap finite impulse response (FIR) filter to produce equalized data bits.
A receiver equalizer, comprising:
- means for sampling the input data stream according to plural phases of a sampling clock to produce data samples;
- and
- means for filtering the data samples with an analog multi-tap finite impulse response (FIR) filter to produce equalized data bits;
- means for sampling and holding the equalized data bit values;
- and
- means for converting the sampled equalized data bit values to digital values.
A multi-tap analog finite impulse response filter, comprising:
- a first current source that produces a first current which is proportional to a product of a previous data sample and a weight associated with said previous data sample tap;
- and
- a second current source that produces a second current which is proportional to an instance data sample;
- an adder circuit which subtracts the second current from the first current to produce a third current;
- and
- a converter circuit which converts the third current to a voltage corresponding to the equalized data bit.
A multi-tap analog finite impulse response filter method, comprising:
- producing a first current which is proportional to a product of a previous data sample and a weight associated with said previous data sample tap;
- producing a second current which is proportional to an instance data sample;
- subtracting the second current from the first current to produce a third current;
- and
- converting the third current to a voltage corresponding to the filtered data bit.
A multi-tap analog finite impulse response filter, comprising:
- means for producing a first current which is proportional to a product of a previous data sample and a weight associated with said previous data sample tap;
- means for producing a second current which is proportional to an instance data sample;
- means for subtracting the second current from the first current to produce a third current;
- and
- means for converting the third current to a voltage corresponding to the filtered data bit.
Dependencies are inferred from the claim text.