A novel architecture and design technique for phase-equalized low-sensitivity digital LDI ladder filters

A technique for designing phase-equalized low-sensitivity ladder filters for digital LDI (lossless discrete integrator) leap-frog implementation is presented. These filters are nonminimum phase filters. The approximation problem is divided into separate phase and amplitude approximations. A new filter architecture is also presented to implement complex zeros outside the unit circle. This circuit, lossless and doubly terminated, retains the optimal amplitude sensitivity of the passive distributed circuit. This new structure retains the modularity and regularity of the original ladder filters, making it suitable for VLSI implementation. It can be applied to a variety of applications that require a phase-equalized recursive filtering, such as data and video communications.<>