Comparison of the Gray and binary encoders in high-speed ADC

To realize the encoder in the high-speed ADCs (analog-to-digital converter), the comparisons between gray and binary encoders which are often used in the ADCs are discussed. With the considerations of the errors sources, error distribution, total power and circuit scale in actual working, the comparisons are discussed and the results show that the two encoding methods have the respective disadvantages and advantages under different application conditions. The binary encoder has more advantages than the gray encoder at lower quantized bits. Based on a 6-bit high-speed ADC, a high-speed binary encoder is designed in SMIC 0.18 μm CMOS (complementary metal oxide semiconductor) technology. The measurement of the chip shows the encoding circuit can work well at high speeds up to 2 GHz.