Method for determining filter coefficients of a digital filter and digital filter

1. A method, comprising:

determining a plurality of filter coefficients for a digital filter for a Universal Mobile Telecommunication System (UMTS), the determining including:

dividing initial filter coefficient by a scaling factor, to result in a plurality of scaled filter coefficients:

quantizing the scaled filter coefficient so that only a certain maximum number (n) of “1” bits are counted from a most significant bit onwards:

determining a respective quantization error of each quantized scaled filter coefficient relative to a respective one of the initial filter coefficients; and

repeatedly modifying for a number of times the scaling factor and determining which scaling factor results in a quantization error having minimal error value, and

implementing in the filter the filter coefficients resulting in the minimal error value.

2. A method as claimed in claim 1 , wherein the number (n) comprises one of four, three, or two.

3. A method as claimed in claim 1 , wherein if again a “1” bit follows the last “1” bit, a rounding is effected from the last bit onwards.

4. The new method according to claim 1 , further comprising multiplying an input by 2 j by shifting the input by i and summing shifted values using a plurality of adders.

5. The method according to claim 4 , wherein the multiplying is performed using a plurality of multipliers, the method further comprising selectively connecting the multipliers with the adders using a programmable selector in accordance with a programming.

6. The method according to claim 1 , further comprising:

multiplying an input by 2 j by shifting the input by i using a multiplier formed by connections of inputs and outputs.

7. A digital filter for a Universal Mobile Telecommunication System (UMTS), comprising

means for dividing a plurality of binary filter coefficients by a scaling factor to result in a plurality of scaled filter coefficients;

means for quantizing the scaled filter coefficients so that they do not exceed a selected number (n) of “1” bits from a most significant bit onwards; and

adder stages for processing the scaled and quantized filter coefficients with an input signal.

8. The digital filter as claimed in claim 7 , comprising a final stage for processing an output signal by a factor reciprocal to the scaling factor.

9. A digital filter as claimed in claim 7 , wherein each adder stage comprises n−1 adders and means for multiplying an input by 2 i by shifting the input by i, the input being a respective one of the scaled and quantized filter coefficients.

10. A digital filter as claimed in claim 7 , wherein the adder stages include first and second adder stages respectively including:

respective numbers of multiplying means for multiplying an input by 2 i by shifting the input by i, wherein the respective numbers of multiplying means are different: and

respective numbers of adders coupled to the respective multiplying means, wherein the respective numbers of adders are different.

11. A digital filter as claimed 10 , wherein the adder stages include a third adder stage having only a single multiplying means for multiplying an input by 2 j by shifting the input by i.

12. A digital filter as claimed in claim 7 , wherein each adder stage comprises n-1 adders and means for multiplying an input by 2 j by shifting the input by i, the input being a respective one of the scaled and quantized filter coefficients, wherein each of the means for multiplying the input by 2 i by shifting the input by i is formed by connections of inputs and outputs of a multiplier stage.

13. A digital filter as claimed in claim 7 , wherein each adder stage comprises:

n-1 adders;

multiplying means for multiplying an input by 2 j by shifting the input by j, the input being a respective one of the scaled and quantized filter coefficients; and

a programmable selector which in accordance with programming connects the multiplying means with the adders.

14. A method, comprising:

producing a plurality of scaled filter coefficients by dividing initial filter coefficients by a scaling factor;

quantizing the scaled filter coefficients so that only a certain maximum number (n) of “1” bits are counted from a most significant bit onwards;

determining respective quantization errors of the quantized scaled filter coefficients relative to the initial filter coefficients, respectively; and

modifying the scaling factor and determining which scaling factor results in a quantization error having minimal error value, and

implementing in the filter the filter coefficients resulting in the minimal error value.

15. A method as claimed in claim 14 , wherein the number (n) comprises one of four, three, or two.

16. A method as claimed in claim 14 , wherein if again a “1” bit follows the last “1” bit, a rounding is effected from the last bit onwards.

17. The method according to claim 14 , further comprising:

multiplying an input by 2 j by shifting the input by i using a multiplier formed by connections of inputs and outputs.

18. The method according to claim 14 , further comprising

multiplying an input by 2 j by shifting the input by i and summing shifted values using a plurality of adders.

19. The method according to claim 18 , wherein the multiplying is performed using a plurality of multipliers, the method further comprising selectively connecting the multipliers with the adders using a programmable selector in accordance with a programming.