Expanding the time-interleaving design capabilities: A 28 GS/s4-bit time-interleaved current-steering DAC case study

In this work, a novel approach of designing high-speed time-interleaved Digital-to-Analog Converters (DACs), that exploits high-order time-interleaved factors, was proposed. The presented time-interleaving design approach is based on the current superposition principle, capable of expanding the time-interleaved factor of DACs without compromising the conversion linearity and accuracy. For the validation of the proposed design approach, a 28 GS/s 4-bit 4 x Time-Interleaved current-steering DAC was designed using a 22 nm Fully-Depleted Silicon-On-Insulator (FDSOI) CMOS process node. Post-layout simulations were carried out by developing a custom, hybrid RC/RLCk parasitic extraction methodology, capable of capturing all possible layout parasitic effects due to the high conversion speed of the designed DAC. Using the proposed approach, the designed time-interleaved DAC was capable of achieving ENOB>3.83 bits, SFDR>28.7 dBc for f(in)<= 1.75 GHz, with no missing codes and a low power consumption of P-diss=3.1 mW/core.