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Summary: This paper presents an energy‐efficient fully differential switching scheme for successive approximation register (SAR) analog‐to‐digital converters (ADCs). During the sampling phase, the top and bottom plates of all capacitors except most significant bit (MSB) capacitors are grounded in digital‐to‐analog converter (DAC) arrays. The input signals are bottom plate sampled on MSB capacitors. This technique can reduce the settling time by more than 87.5% in comparison with the conventional switching scheme. Furthermore, a novel reset‐free regenerative comparator is unveiled in this paper. The proposed comparator is armed to amplify its inputs both during the reset and evaluation phases. In comparison with a conventional single‐ended comparator, the proposed comparator can reduce power consumption above 90% for the almost same input‐referred offset voltage. The proposed scheme is designed with a resolution of 8‐bit and a sampling rate of 90 MS/s in a standard 65‐nm CMOS technology. The simulation results certify that the ADC dissipates 363‐μW power with a 1.2‐V supply voltage and achieves a 7.13 effective number of bits (ENOBs), yielding a 28.8 fJ/conversion step Nyquist rate Walden FOM. [ABSTRACT FROM AUTHOR]

In this letter, a new rail‐to‐rail two‐stage regenerative comparator for low supply voltage applications is presented. A rail‐to‐rail operation is achieved by utilizing an inverse inverter pre‐amplifier. The proposed comparator is post‐layout simulated within a standard 180‐nm CMOS technology. In the worst‐case scenario, the energy efficiency and the delay of the comparator are improved by more than 80% compared to the conventional single‐stage comparator. [ABSTRACT FROM AUTHOR]

Summary: This paper unveils two efficient free running (FR) quenching circuits with the aim of reducing quenching time (QT) to minimize avalanche charge. Likewise, one circuit is compactly designed with low power consumption, suitable for single‐photon avalanche diode (SPAD) with hold‐off time below 10 ns. In second circuit, tunable hold‐off and reset‐time are provided within a wide range without decreasing QT, which are desirable in many applications. Proper operation and circuit uncertainty is assessed by Monte Carlo analysis in a standard 90‐nm complementary metal‐oxide semiconductor (CMOS) technology. In a bid to do a comparison between previously reported circuits and the proposed circuits, they are simulated with same SPAD model and parameters and results corroborate the proposed circuits guarantee active quenching time (AQT) of below 1 ns. Proposed circuits with current and area consumption of 0.74 μA, 32 μm2 for 7‐ns dead time and 16.2 μA, 93 μm2 for 21‐ns dead time are more efficient in terms of QT, area, and power consumption in comparison with other works. [ABSTRACT FROM AUTHOR]

This paper presents a high-speed common-mode insensitive two-stage regenerative comparator designed for low supply voltage applications. The proposed comparator features a doubled transistor latch that enables rail-to-rail operation, which is pioneered to the best of the author's knowledge. The voltage swing of output nodes of the pre-amplifiers is limited to reduce the power consumption. This limitation boosts the regeneration speed of the doubled transistor latch. The proposed comparator realized by a standard 65 nm CMOS technology. The post-layout simulation results corroborate that the proposed comparator with 50 MHz sample rate and 0.6 V supply voltage dissipates 3.4 µW power, and occupies 168 µm2 area. Also, the offset voltage variation within the full common-mode range can be below 2 mV. In a worst-case scenario compared to the conventional single-stage comparator, the proposed comparator improves delay and energy efficiency by more than 80%. Considering its overall performance, this energy-efficient comparator is suitable for all low supply voltage applications, including Internet of Things (IoT), successive approximation registers analog-to-digital converters (SAR ADCs), and biomedical implants. [ABSTRACT FROM AUTHOR]

A state-of-the-art energy-efficient digital-to-analog converter (DAC) switching scheme suitable for single-ended successive approximation register (SAR) analog-to-digital converter (ADC) is proposed in this paper. The proposed scheme synthesizes two reference voltages V r e f and V q to generate relevant voltage levels. The reference voltage V q is a quarter of the V r e f. To ease logic design, the V r e f is only utilized during the third phase of conversion with the MSB capacitor of each DAC. The proposed scheme reduces DAC's average switching energy and the area by 94.44 % and 50 % in comparison with the conventional single-ended scheme. Furthermore, a novel 3-stage common-mode insensitive regenerative comparator is proposed to reduce non-linearity errors caused by common-mode voltage variations of DAC. The proposed single-ended ADC is simulated in a standard 65-nm CMOS technology with a resolution of 8-bit and sampling rate of 25 MS/s. The simulation results corroborate that the ADC consumes 124 µW power with 1.2 V supply voltage and attain a 7.23 effective number of bits, resulting in a 33fJ/conversion step FOM. [ABSTRACT FROM AUTHOR]