A binary-to-thermometer decoder with redundant switching sequences

This paper presents a practical realization of a binary-to-thermometer decoder with redundant output switching sequences. Its particular application is to decode the DAC segmented MSB part. In the presented realization, 4 MSB binary bits are decoded to 15 thermometer bits through 2 different thermometer switching sequences. The end-user can choose the decoding switching sequence, according to the distribution of the mismatch errors of the DAC signal current sources. Therefore, the chip yield INL Yield , which is defined as the percentage of DAC samples that meet some specifications, is expected to improve by more than 12% for barriers 95% INL Yield > . The presented realization proves the efficiency of this approach based on two main considerations: area and power consumption. The silicon area of the decoder is increased by only 50%, while for the whole DAC area, this increase is under 3%. On the other hand, the power consumption of the decoder is doubled but it is still under 0.5% of the entire DAC power consumption. These results prove not only the efficiency of the presented particular realization but also the high efficiency of the redundant switching sequences for the DAC MSB thermometer current sources. The article concludes with general discussion and further possible enhancement of the new decoder and the presented realization.