Two‐step reset method for energy‐efficient SAR ADC switching schemes

Abstract

The impact of the reset energy on the overall energy efficiency of an successive-approximation register (SAR) ADC is examined for some recently reported switching schemes. The reset energy can several times exceed the switching energy drawn from the reference during conversion. The simple method based on the optimal capacitor charging is proposed. By utilising of two-step switching during the reset phase, the total energy consumption of the DAC's capacitive matrix can be decreased by ∼20%.

A 7.1-fJ/Conversion-Step 88-dB SFDR SAR ADC With Energy-Free “Swap To Reset”

“…[7]- [9] also save conversion energy, but they consume a reset energy that is 0.9×, 1.5×, and 2.2× the conversion energy, respectively. Techniques to save reset energy were introduced in [10] and [11], but these works require a third reference voltage (V CM ) and only include behavioral simulations without experimental validation.…”

Energy‐efficient capacitor‐swapping reset scheme with MSB‐split DAC for SAR ADCs

“…In capacitive DAC (CDAC)-based SAR ADCs, the switching energy consumed by CDAC is considerable during a SAR conversion cycle. Recently, various techniques have been developed to reduce the switching energy of CDAC arrays [1][2][3][4][5][6][7][8]. Compared with the conventional scheme, the V cm -based scheme [2], the switchback scheme [3] and Zhu [4] achieve a switching energy reduction of 87.5, 90.6 and 98.8%, respectively.…”

“…Taking the switching energy and the reset energy into consideration to evaluate a switching scheme is more reasonable, as sometimes the reset energy is much higher than the switching energy [3][4][5]. To reduce the reset energy, a two-step reset method [6] and a swap-to-reset method [7] are developed. However, schemes in [6,7] only reduce the reset energy to some extent and complicate the control logic simultaneously.…”

“…To reduce the reset energy, a two-step reset method [6] and a swap-to-reset method [7] are developed. However, schemes in [6,7] only reduce the reset energy to some extent and complicate the control logic simultaneously. In this Letter, an energy-efficient scheme is proposed for SAR ADC.…”

“…Thus, significant energy saving is achieved compared with the schemes in [3][4][5]. Besides, the implementation of the CSR scheme only needs to change connections of the four sub-arrays, resulting in less complexity of the control logic compared with the two-step reset method in [6] and swap-to-reset scheme in [7]. Comparison of existing switching schemes: The behavioural simulations for a 10-bit SAR ADC were performed in MATLAB to compare the proposed scheme with other existing ones.…”