A Prototype Programmable Digital LDI Filter Circuit
Freddy Balestro, J. Chan Yan Fong, Gilles Privat, Mohamed Tawfik, Alain Wittmann, I. Vandeweerd · 1990
A prototype chip implementing a 7-th order pole-zero low-pass digital LDI ladder filter with programmable coefficients has been fabricated in 1? CMOS technology. Its complexity is 17000 transistors, with an area of 3 mm2. This circuit was designed as a test vehicle for a fully integrated VLSI function compiler, that takes as input the frequency specifications of a filter. New and unique LDI structures are used, which are especially well suited to this design approach : their excellent properties with respect to finite-arithmetic effects result in optimum hardware complexity, while their modularity and regularity lead to a very simple placement and densely packed layout, with minimal routing overhead. The bit-serial systolic architecture adopted allows to operate up to 50 MHz