Ultra Compact and Linear 4-bit Digital-to-Analog Converter in 22nm FDSOI Technology

This work presents two 4-bit resistor-string digital-to-analog converters (R-DAC) designed in 22nm FDSOI technology. Both DACs are connected to a shared resistor string to make the final layout more compact. The small on-resistance of the Transmission-Gate (TG) switches designed in the FDSOI node yields a low Internal non-linearity (INL) and Differential non-linearity (DNL) in the DACs output. The effect of the temperature variations on the linearity performance of the DACs is also studied. It is shown that the temperature gradients can be compensated for by equally distributing the switches on the layout area. Post-layout simulations show an approximately fixed INL and DNL of, respectively, 0. 17LSB and 0. 1LSB over a wide temperature range from -40°C to $125^{0} C$. Two R-DACs dissipate the static/dynamic power of 0. 12/0.155mW with the layout size of only 70 $\mu m^{2}$, showing a high performance for two 4-bit DACs.