VLSI programmable digital filter for video signal processing

High speed digital filtering is required in real time video signal processing, as well as high order filters are needed to match television studio signal quality. The hardware complexity involved by such system constraints may be faced by a two-fold approach, concerning both the architecture and the technological aspects of a specific electronics device devoted to the above task. This article deals with a processor especially developed for the purpose of fast digital video signal applications, such as filtering, equalization, interpolation and so on. The nonrecursive transposed F.I.R. (Finite Impulse Response) structure has been selected, which exhibits a linear phase behavior. A novel approach has been developed for the multipliers implementation, by optimizing an EPROM based look-up table storing the products between all video samples and the filter coefficients significant bits, resulting in a programmable system. The Programmable Filter Processor has been designed with a high level of parallelism and pipelining and a 1.2 μm CMOS EPROM, single metal technology has been employed for the integration process of the chip. This has been successfully production-tested for 40 Msamples/s throughput rate, thus both allowing to meet most video filtering applications and demonstrating the potentialities of nonvolatile memory technologies in embedded applications. Moreover multiple devices can be interconnected to yield multiprocessor structures for more demanding performances such as, cascaded or longer filters, input signal precision extension, computation improved accuracy, increased throughput rate, and two-dimensional signal processing.