Accurate Multi-bit Feedback DAC Dedicated to High-speed Continuous-time DS Converters
Résumé
This paper presents the behavioral modeling and circuit design of an accurate multi-bit DAC dedicated to high speed Continuous-time DS converters. The multi-bit DAC element mismatch is modeled, demonstrating that the non-linearities coming from the feedback DACs is awful for Continuous-time DS modulators. The proposed DAC is dimensioned in order to achieve best matching, reaching an unit current source relative standard deviation up to 0.7%. A full high-speed Continuous-time DS converter is implemented using the accurate DAC, achieving a SNR of 76 dB in a widebandwidth of 20 MHz.