Articles | Volume 11
Adv. Radio Sci., 11, 227–230, 2013
https://doi.org/10.5194/ars-11-227-2013
Adv. Radio Sci., 11, 227–230, 2013
https://doi.org/10.5194/ars-11-227-2013

  04 Jul 2013

04 Jul 2013

Implementation of a digital trim scheme for SAR ADCs

J. Bialek1, A. Wickmann2, F. Ohnhaeuser2, G. Fischer1, R. Weigel1, and T. Ussmueller1 J. Bialek et al.
  • 1University of Erlangen-Nuremberg, Departement of Electrical Engineering, Erlangen, Germany
  • 2Texas Instruments Deutschland GmbH, Germany

Abstract. Successive approximation register (SAR) analog-to-digital Converters (ADC) are based on a capacitive digital-to-analog converter (CDAC) (McCreary and Gray, 1975). The capacitor mismatch in the capacitor array of the CDAC impacts the differential non-linearity (DNL) of the ADC directly. In order to achieve a transfer function without missing codes, trimming of the capacitor array becomes necessary for SAR ADCs with a resolution of more than 12 bit. This article introduces a novel digital approach for trimming. DNL measurements of an 18 bit SAR ADC show that digital trimming allows the same performance as analog trimming. Digital trimming however reduces the power consumption of the ADC, the die size and the required time for the production test.