A Low-Energy and Area-Efficient Vaq-Based Switching Scheme with Capacitor-Splitting Structure for SAR ADCs

A Hybrid Energy-Efficient, Area-Efficient, Low-Complexity Switching Scheme in SAR ADC for Biosensor Applications

“…The advantages of the switching scheme proposed in this paper are not only in the high energy savings, but also in the high area savings. Similar energy savings schemes have been presented by Li et al [ 14 ] and Huang et al [ 18 ]; however, their designs also have their own characteristics. In the scheme by Li et al [ 14 ], C/2 is used as the unit capacitor, a bridge switch is applied for in the second conversion step, and all capacitors are connected to V cm , which is highly dependent on the V cm .…”

“…Moreover, MAS [17] uses floating technique that achieves higher energy efficiency; however, the scheme presented in this study has fewer total unit capacitors, achieving an 87.5% area reduction with excellent energy savings. The scheme presented by Huang et al [18] is similar to that presented in this paper in terms of its DAC circuit structure; both use the MSB capacitor-splitting technique and additional reference V aq , but the difference between the two is that V aq is only used in the last two reference voltage switches for the proposed scheme. Huang et al [18] use V aq throughout the comparison, and its scheme does bring higher energy efficiency and effectively reduces the capacitor area, resulting in a larger common-mode voltage variation, which improves the dependence of the overall circuit on V aq , and increases the complexity in the design of the drive circuits.…”

“…The scheme presented by Huang et al [ 18 ] is similar to that presented in this paper in terms of its DAC circuit structure; both use the MSB capacitor-splitting technique and additional reference V aq , but the difference between the two is that V aq is only used in the last two reference voltage switches for the proposed scheme. Huang et al [ 18 ] use V aq throughout the comparison, and its scheme does bring higher energy efficiency and effectively reduces the capacitor area, resulting in a larger common-mode voltage variation, which improves the dependence of the overall circuit on V aq , and increases the complexity in the design of the drive circuits. Compared to Huang’s scheme, the advantages of the scheme presented in this paper include a lower common-mode voltage variation and lower dependence on V aq .…”

“…That of the C-2C common-mode voltage structure DAC can be reduced by 90.61% [ 9 ], that of the tri-level structure DAC can be reduced by 97.66% [ 10 ], that of the common-mode voltage monotonic (VMS) structure DAC can be reduced by 96.89% [ 11 ], and that of the hybrid capacitor structure DAC be reduced by 98.83% [ 12 ]. In addition to these, schemes have also been presented by Wang et al [ 13 ], Li et al [ 14 ], Sanyal et al [ 15 ], Wu et al [ 16 ], MAS [ 17 ], and Huang et al [ 18 ], achieving energy savings of 98.1%, 98.0%, 98.4%, 98.43%, 98.45%, and 99.5%, respectively. ERMS [ 9 ] uses the C-2C dummy capacitor, which reduces the overall area and the number of switches, improving energy efficiency.…”

“…Furthermore, all capacitors are switched by three reference voltages, which increases the complexity of the logic circuit. The scheme by Huang et al [ 18 ] has a higher energy efficiency, and at the same time, it suffers from higher common-mode voltage variation as V aq appears throughout the comparison, raising the dependence on V aq . Wu et al [ 16 ] and MAS [ 17 ] use a floating technique that replaces the additional reference voltage, achieves higher energy efficiency, lower common-mode voltage variation, and reduces the dependence on the additional reference voltage.…”