1.5 mu m CMOS gate arrays with analog/digital macros designed using common base arrays

Mixed analog and digital circuits are realized on a 1.5 mu m silicon-gate CMOS chip with +5 V power supply only. The circuit uses CMOS digital gate arrays of 0.32 K to 19.6 K cells and is created without any additional turnaround time or any restriction on the design. Typical internal digital gate (two-input NAND) speed, with a fanout of 3 and a wire length of 3 mm, is 1.4 ns. A voltage comparator with +or-8 mV maximum input offset voltage and 60 ns response time, digital-to-analog and analog-to-digital converters with 4-, 6-, and 8-bit resolution, respectively, and an analog switch of 25 Omega on-resistance can be realized on the same chip with digital circuits. Using this technology, about one-tenth of the turnaround time can be achieved compared with full-custom LSIs for the same system. The product development flow and computer-aided-design tools for designing mixed analog and digital gate arrays are the same as for digital gate arrays. >