VCO‐based ADC with a simplified DAC for non‐linearity correction. Issue 13 (1st June 2018)

• Record Type: Journal Article
• Authors: Quintero, A.; Perez, C.; Gutierrez, E.; Hernandez, L.
• Is Part Of: Electronics letters. Volume 54:Issue 13(2018)
• Page Start: 813
• Page End: 815
• Publication Date: 2018-06-01
• Subjects: voltage‐controlled oscillators -- digital‐analogue conversion -- circuit feedback -- distortion -- compensation -- sigma‐delta modulation -- quantisation (signal); VCO‐based ADC -- simplified DAC -- nonlinearity correction -- open‐loop ADC performance -- VCO nonlinearity -- first‐order noise shaping -- resolution limitation -- ring oscillator VCO -- feedback loop -- distortion compensation -- Leslie‐Singh sigma‐delta modulator -- ΣΔ modulator -- distortion correction loop -- quantisation levels -- system‐level architecture; Electronics -- Periodicals; 621.381
• DOI: 10.1049/el.2018.1000
• Languages: English
• ISSNs: 0013-5194

Abstract

Abstract : 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.