Design of a single-chip digital lattice equalizer filter

One lattice equalizer stage is designed on a single chip using 4-μm NMOS technology. All the arithmetic operations of the chip are performed bit-serially under the control of a global two-phase clock, and they are totally pipelined. The data are represented as 16-bit two´s complement fixed-point numbers. A built-in test scheme allows the offline testing of the chip with high fault coverage at a minimal hardware overhead. Direct coupling between chips permits the realization of filters of higher order. In addition, the structure of the lattice equalizer permits the use of the same chip in linear prediction problems. SPICE simulation results and fabrication of the major blocks in the design demonstrated that operating clock frequencies of up to 8 MHz are possible. At the maximum estimated operating clock frequency, the chip can accommodate applications with data rates of up to 500 kHz.