Energy‐efficient hybrid capacitor switching scheme for SAR ADC

Abstract

A novel low-energy hybrid capacitor switching scheme for a lowpower successive approximation register (SAR) analogue-to-digital converter (ADC) is presented. The proposed switching scheme combines a new switch method and the monotonic technique. The new switch method can achieve no switching energy consumption in the first three comparison cycles. Furthermore, a low-energy monotonic procedure is performed for the rest of the comparisons. The average switching energy is reduced by 98.83% compared with the conventional architecture, resulting in the most energy-efficient switching scheme among the existing switching techniques. Besides the significant energy saving, the proposed switching scheme also achieves a 75% reduction of the capacitors over the conventional scheme.

Variable resolution SAR ADC architecture with 99.6% reduction in switching energy over conventional scheme

“…3a and b provide an illustration of the waveforms of the hybrid capacitor switching scheme [4] and the proposed technique. As it is shown, the commonmode voltage of the proposed switching scheme will monotonically approach V cm .…”

“…Recent state-of-the-art has introduced several techniques to reduce the switching energy. Compared to the conventional architecture, the new tri-level [1], Sanyal and Sun [2], asymmetric monotonic [3] and hybrid capacitor [4] reduce the switching energy by 96.89%, 98.4%, 98.5% and 98.83%, respectively. The switching architecture in [5] employing the previous bits to control the splitting capacitors of the sub-DAC has significant energy consumption from the first two comparison cycles, and wastes the same large capacitor area as the conventional scheme.…”

Energy-efficient hybrid split capacitor switching scheme for SAR ADCs

“…In SAR ADC designs, DAC switching is one of the major consuming source. Recently, many studies [1,2,3,4,5,6,7,8,9,10] have been conducted to reduce the power of the DAC switching to get better energy efficiency. Compared to the conventional switching sequence, the charge averaging switching (CAS) [2] technique achieves 74.76% savings in switching energy.…”

“…Compared to the conventional switching sequence, the charge averaging switching (CAS) [2] technique achieves 74.76% savings in switching energy. The Merged-capacitor switching [4] or Vcmbased [5] switching procedure has an energy reduction of 87.51% whereas the trilevel [7] and the hybrid capacitor [10] schemes achieve remarkable 96.89% and 97.66% reductions, respectively. In this letter, the proposed switching scheme consumes no switching energy in the first three comparison cycles.…”

“…In [7,10], the ADC continues with the normal monotonic switching procedure for the subsequent comparisons. To further reduce the power, the combined monotonic and charge sharing switching method is utilized.…”