Open AccessVCO‐based ADC with a simplified DAC for non‐linearity correction
Author(s) -
Quintero A.,
Perez C.,
Gutierrez E.,
Hernandez L.
Publication year - 2018
Publication title -
electronics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.375
H-Index - 146
ISSN - 1350-911X
DOI - 10.1049/el.2018.1000
Subject(s) - voltage controlled oscillator , linearity , noise shaping , electronic engineering , phase noise , ring oscillator , computer science , distortion (music) , delta sigma modulation , noise (video) , control theory (sociology) , engineering , voltage , cmos , electrical engineering , amplifier , artificial intelligence , control (management) , image (mathematics)
The performance of open‐loop ADCs implemented with VCOs is limited by VCO non‐linearity and first‐order noise shaping. The resolution limitation imposed by first‐order noise shaping can be compensated by a ring oscillator VCO with many output phases. Linearity can also be improved by using a feedback loop around the VCO closed with a DAC. However, a long ring oscillator may require a DAC with a prohibitive number of bits if feedback is used to compensate distortion. This Letter proposes an ADC architecture based on the Leslie‐Singh Sigma‐Delta ( Σ Δ ) modulator that allows to implement a distortion correction loop around a VCO with a simplified DAC of few levels, yet keeping a large number of output quantisation levels to maintain resolution. The Letter discusses the system‐level architecture and shows an implementation circuit example to verify the effective correction of distortion.