Patent ID: 6961680

Claim:
A digital filter comprising a device that synthesizes a digital signal processing difference equation: H ⁡ ( z ) = Y ⁡ ( z ) X ⁡ ( z ) = ∑ i = 0 r ⁢ L i · z - i 1 + ∑ j = 1 m ⁢ K j · z - j where: H(z)=Z-transform of filter response Y(z)=Z-transform of output response X(z)=Z-trans form of input response r=Number of input sample coefficients m=Number of output sample coefficients L i =Gain (tap weights) for the input sample data K j =Gain (tap weights) for the output sample data z −i =Z-transform of the discretized version of an input delayed by i samples z −j =Z-transform of the discretized version of an output delayed by j samples said digital filter is synthesized by replacing elements of said digital signal processing difference equation with an optical component as follows: each memory element z −i and z −j is replaced with a delay unit; each sum block Σ is replaced with a combiner; each gain block element L i and K j is replaced with an amplifier or an attenuator; and each T-junction between each pair of delay units is replaced with a splitter.