Multi-output passive digital filters

In this paper, a new family of four multi-output second-order passive digital filters constructed from four passive digital two-ports are presented. The conditions for passivity in a passive digital two-port are first defined. Four passive two-ports are introduced, their passivity and stability constraints on coefficients, and pseudopower expressions are derived. The general forms of the second-order lowpass, highpass, bandpass, bandstop, and allpass transfer functions of these four multi-output passive digital filters are given. Zero-input and constant-input oscillations can be eliminated by magnitude truncation. The hardware complexity and input to output latency performance of these four passive digital filters are analyzed. Simulation results on the amplitude scaling, coefficient sensitivity, and quantized pole plots of these passive digital filters are given.