Real-time programmable unit-element SC filter for LPC synthesis

The letter presents a novel programmable unit-element SC filter for LPC synthesis. The circuit is based on the theory of wave-flow networks. It has the advantage that for a programmable 10th-order unit-element SC filter only five programmable capacitor arrays are needed. The capacitive loading of every op amp is constant, thus simplifying the op amp design. The circuit is insensitive to stray capacitances which are commonly associated with integrated MOS capacitors and transistors. It also exhibits a low sensitivity to coefficient quantisations; hence, the circuit is well suited for integration in MOS technology.