Piecewise linear operations on sigma-delta modulated signals

Piecewise linear (PWL) circuits operating on sigma-delta (ΣΔ) modulated signals are proposed. The proposed circuit library includes an absolute circuit, a min/max selector and a negative resistance. As an application of the PWL circuits, a median filter is presented. It is structured with 23% of logic gates consumed by an equivalent filter with 8-bit parallel signal form. It is expected that application of ΣΔ domain signal processing including proposed PWL operations to other modern information processing and communication systems such as neural networks and chaotic communication systems will reduce their hardware cost.