Receiver and low power digital filter therefor

A receiver including a digital filter comprising:

• at least two multiple stage shift registers;
• a plurality of multipliers corresponding in number to the total number of stages in the at least two multiple stage shift registers, each multiplier receiving as a first input an output from a stage of the at least two multiple stage shift registers:
• a tap weight shifter coupled to a tap weight source to receive tap weights, the tap weight shifter coupled to provide a second input to each multiplier, the tap weight shifter capable of shifting tap weights, each multiplier producing an output corresponding to a product of the first and second inputs;
• and
• an adder for summing the multiplier outputs to provide a sum output, wherein:
• two or more sum outputs are generated by the adder between consecutive shiftings of new data into the at least two multiple stage shift registers;
• and
• no new data is shifted into any of the at least two multiple stage shift registers between generation of a first of the two or more sum outputs by the adder and a last of the two or more sum outputs by the adder.

A method of filtering digital data, comprising the steps of:

• a. shifting digital data into first and second multiple stage shift registers;
• b. multiplying an output from each stage of the first and second multiple stage shift registers by an associated, respective tap weight to produce a plurality of products;
• c. combining the plurality of products to form a single sum;
• d. circularly shifting the tap weights;
• and
• e. repeating steps b and c at least once before step a is repeated.

A method of filtering data, comprising the steps of:

• a. shifting data into N multiple stage shift registers, each of the N multiple stage shift registers having at least L stages, N and L being integers, N being greater than 2;
• b. multiplying an output from each of the at least L stages of the N multiple stage shift registers by a corresponding tap weight to produce a plurality of products;
• c. combining the plurality of products to form a single sum;
• d. circularly shifting the tap weights;
• e. repeating steps b, c, and d N−2 times before step a is repeated;
• f. repeating steps b and c again before step a is repeated.

A digital filter comprising:

• N multiple-stage shift registers, N>1;
• a tap changer adapted to store a configuration of tap weights;
• a plurality of multiplying elements, each multiplying element adapted to (a) receive (i) a datum from a corresponding stage of a corresponding shift register and (ii) a corresponding tap weight from the tap changer and (b) generate an output corresponding to a product of the datum and the corresponding tap weight;
• and
• an adder adapted to receive the output from each multiplying element and generate a sum corresponding to the sum of the products of all of the data in the N multiple-stage shift registers and the corresponding tap weights in the tap changer, wherein:
• the adder is adapted to generate two or more different sums for each set of data stored in the N multiple-stage shift registers;
• no new data is shifted into any of the N multiple-stage shift registers between generation of a first of the two or more different sums by the adder and a last of the two or more different sums by the adder;
• and
• each different sum is based on a different configuration of tap weights in the tap changer.

A receiver including a digital filter, the digital filter comprising:

• N multiple-stage shift registers, N>1;
• a tap changer adapted to store a configuration of tap weights;
• a plurality of multiplying elements, each multiplying element adapted to (a) receive (i) a datum from a corresponding stage of a corresponding shift register and (ii) a corresponding tap weight from the tap changer and (b) generate an output corresponding to a product of the datum and the corresponding tap weight;
• and
• an adder adapted to receive an output from each multiplying element and generate a sum corresponding to the sum of the products of all of the data in the N multiple-stage shift registers and the corresponding tap weights in the tap changer, wherein:
• the adder is adapted to generate two or more different sums for each set of data stored in the N multiple-stage shift registers;
• no new data is shifted into any of the N multiple-stage shift registers between generation of a first of the two or more different sums by the adder and a last of the two or more different sums by the adder;
• and
• each different sum is based on a different configuration of tap weights in the tap changer.