Open AccessHigh‐linearity SAR‐VCO MASH ΔΣ ADC with second‐order noise shaping
Author(s) -
Payandehnia P.,
Maghami H.,
Mirzaie H.,
Temes G.C.
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.2018.6779
Subject(s) - voltage controlled oscillator , noise shaping , linearity , electronic engineering , successive approximation adc , noise (video) , signal to noise ratio (imaging) , computer science , control theory (sociology) , voltage , comparator , electrical engineering , engineering , telecommunications , artificial intelligence , image (mathematics) , control (management)
A novel 0‐2 Multi‐Stage Noise Shaping (MASH) analogue‐to‐digital converter (ADC) is proposed. The first stage is implemented using a 4‐bit SAR ADC. The second stage uses a voltage controlled oscillator (VCO)‐based quantiser (VCOQ). Unlike earlier VCOQs which provide first‐order noise shaping, the VCOQ proposed in this Letter achieves second‐order noise filtering. To implement this noise shaping, the quantisation noise of the VCOQ is extracted as a pulse‐width‐modulated signal, and it is fed back to the VCO input using a charge pump circuit. In the proposed scheme, the input signal to the VCO is small. Therefore, the linearity requirement of this block is relaxed. Also, any error related to the charge pump circuitry will be first‐order shaped at the output. Simulation results confirm the second‐order noise shaping of the output of the ADC, and an excellent (14‐bit signal‐to‐noise and distortion ratio) performance with the over‐sampling ratio of 16.