A 5-Bit Building Block for 20 MHz NMOS A/D Converters

This paper presents a monolithic, fully parallel 5-bit NMOS A/D converter. The chip is fabricated using a standard metal-gate enhancement/depletion technology with 7 μm minimum features. It contains 31 strobed comparators, latches, combinational logic, a 5 by 31 ROM, TTL buffers and a 4-bit DAC. This makes it a building block for two-step 8-bit converters. The chip was fully characterised at 20 megasamples per seconds. The dc linearity was better than 1/4 LSB for 80 mV step size.

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