A tapped delay line comprising: state variable filter delay elements (1410-N) arranged in a tapped-delay-line configuration, each element comprising an n th -order state variable filter and an m th -order state variable filter configured to operate on a wideband input in parallel and a summer configured to add outputs from the n th - and m th -order state variable filters; tap weights (1420-1... 1420-N) for scaling respective outputs of each state variable filter delay elements (1410-N); and a summer configured to receive inputs from the tap weights and to output a summed output, wherein m=2 and n=2; and wherein the m th -order state variable filter and the n th -order state variable filter each comprise a state variable filter in a control canonical form, the state variable filter comprising: a first, second, third and fourth fractional gain block and a first and a second variable gain block; a first summer configured to combine the outputs of the first and second fractional gain blocks with a wideband input; a first integrator configured to integrate a scaled output of the first summer; the first variable gain block being configured to amplify an output of the first integrator to provide a first amplified signal; each of the first and third fractional gain blocks being configured to scale the first amplified signal; a second integrator configured to integrate the first amplified signal; the second variable gain block being configured to amplify an output of the second integrator to provide a second amplified signal; an output of the second fractional gain block being based on the second amplified signal; the fourth fractional gain block being configured to scale the scaled output of the first summer; a second summer being configured to combine the outputs of the third and fourth fractional gain blocks and a scaled output of the second variable gain block, the output of the second summer providing the output of the state variable filter. state variable filter delay elements (1410-N) arranged in a tapped-delay-line configuration, each element comprising an n th -order state variable filter and an m th -order state variable filter configured to operate on a wideband input in parallel and a summer configured to add outputs from the n th - and m th -order state variable filters; tap weights (1420-1... 1420-N) for scaling respective outputs of each state variable filter delay elements (1410-N); and a summer configured to receive inputs from the tap weights and to output a summed output, wherein m=2 and n=2; and wherein the m th -order state variable filter and the n th -order state variable filter each comprise a state variable filter in a control canonical form, the state variable filter comprising: a first, second, third and fourth fractional gain block and a first and a second variable gain block; a first summer configured to combine the outputs of the first and second fractional gain blocks with a wideband input; a first integrator configured to integrate a scaled output of the first summer; the first variable gain block being configured to amplify an output of the first integrator to provide a first amplified signal; each of the first and third fractional gain blocks being configured to scale the first amplified signal; a second integrator configured to integrate the first amplified signal; the second variable gain block being configured to amplify an output of the second integrator to provide a second amplified signal; an output of the second fractional gain block being based on the second amplified signal; the fourth fractional gain block being configured to scale the scaled output of the first summer; a second summer being configured to combine the outputs of the third and fourth fractional gain blocks and a scaled output of the second variable gain block, the output of the second summer providing the output of the state variable filter. a first, second, third and fourth fractional gain block and a first and a second variable gain block; a first summer configured to combine the outputs of the first and second fractional gain blocks with a wideband input; a first integrator configured to integrate a scaled output of the first summer; the first variable gain block being configured to amplify an output of the first integrator to provide a first amplified signal; each of the first and third fractional gain blocks being configured to scale the first amplified signal; a second integrator configured to integrate the first amplified signal; the second variable gain block being configured to amplify an output of the second integrator to provide a second amplified signal; an output of the second fractional gain block being based on the second amplified signal; the fourth fractional gain block being configured to scale the scaled output of the first summer; a second summer being configured to combine the outputs of the third and fourth fractional gain blocks and a scaled output of the second variable gain block, the output of the second summer providing the output of the state variable filter.