Novel programmable wave-SC filter structure for pole-zero modelling of vocal tract

In the letter a novel programmable wave-SC filter structure is presented which is suitable for implementation of a LPC vocoder including transmission zeros. Owing to distributed arithmetic five basic cells and two new slightly modified cells, which correspond to the nasal branch, are required for the entire SC vocoder. Each cell contains one programmable capacitor array and the capacitive loading of all op-amps is constant. The latter essentially simplifies the op-amp design and allows the use of low-power dynamic amplifiers. The presented structure employs only fully stray-insensitive SC-amphfier and integrator circuits and offers a low sensitivity to coefficient quantisation.