Polar leapfrog filter

A polar leapfrog filter including at least one polar network which comprises a differentiator constituted by an operational amplifier having input and output terminals, and a first integrator for providing negative feedback to said operational amplifier, said first integrator comprising a first capacitor and a first variable transconductance amplifier;

• and a second integrator for providing negative feedback to said first integrator, said second integrator comprising a second capacitor and a second variable transconductance amplifier, and integrators provided at the input and output sides of said filter respectively, wherein the total number of the circuits is selected to provide an odd order and equal order for the filter, and adjacent ones of the circuits are connected with each other in such a manner that leapfrog type negative feedback is effected.

A polar leapfrog filter including a plurality of polar networks, each of which comprises a differentiator constituted by an operational amplifier having input and output terminals, and a first integrator for providing negative feedback to said operational amplifier, said first integrator comprising a first capacitor and a first variable transconductance amplifier;

• and a second integrator for providing negative feedback to said first integrator, said second integrator comprising a second capacitor and a second variable transconductance amplifier;
• integrators provided at the input and output sides of said filter respectively;
• and a further integrator provided between said polar networks, wherein the total number of the circuits is selected to provide an odd order and equal order for the filter, and adjacent ones of the circuits are connected with each other in such a manner that leapfrog type negative feedback is effected.