A .9micron CMOS Digital Adaptive Filter

An 11 tap digital filter chip that operates at speeds in excess of 40 MHz was developed using .9micron cell based CMOS technology. Development cost and schedule demanded a standard cell approach be used, whereas a full custom design might have been the traditional approach for this type of high speed circuits. No pipelining was necessary and the chip can be utilized as either an adaptive or a fixed coefficient FIR filter. The part was specifically developed to serve as an adaptive transversal equalizer in AT&T's long haul Digital Radio communication network, but can also be used in other applications.