This paper proposes a current-mode hysteretic buck converter with a spur-free constant-cycle frequency-hopping controller that fully eliminates spurs from the switching noise spectrum irrespective of ...variations in the switching frequency and operating conditions. As a result, the need for frequency regulation loops to ensure nonvarying switching frequency (i.e., fixed spurs location) in hysteretic controllers is eliminated. Moreover, compared to frequency regulation loops, the proposed converter offers the advantage of eliminating mixing and interference altogether due to its spur-free operation, and thus, it can be used to power, or to be integrated within noise-sensitive systems while benefiting from the superior dynamic performance of its hysteretic operation. The proposed converter uses dual-sided hysteretic band modulation to eliminate the inductor current imbalance that results from frequency hopping along with the output voltage transients and low-frequency noise floor peaking associated with it. Moreover, a feedforward adaptive hysteretic band controller is proposed to reduce variations in the switching frequency with the input voltage, and an all-digital soft-startup circuit is proposed to control the in-rush current without requiring any off-chip components. The converter is implemented in a 0.35-μm standard CMOS technology and it achieves 92% peak efficiency.
Implementing efficient and cost-effective power regulation schemes for battery-powered mixed-signal SoCs is a key focus in integrated circuit design. This paper presents a fully-integrated ...switched-capacitor DC-DC converter in 45 nm digital CMOS technology. The proposed implementation uses digital capacitance modulation instead of traditional PFM and PWM control methods to maintain regulation against load current changes. This technique preserves constant frequency switching while also scaling switching and bottom-plate losses with changes in load current. Therefore, high efficiency can be achieved across different load current levels while maintaining a predictable switching noise behavior. The converter occupies only 0.16 mm 2 , and operates from 1.8 V input. It delivers a programmable sub-1 V power supply with efficiency as high as 69% and load current between 100 μA and 8 mA. Measurement results confirm the theoretical basis of the proposed design.
This paper introduces a new Pulse-Width Modulation (PWM) control scheme for buck regulators that combines phase chopping with frequency hopping to achieve spur-free operation while delivering low ...output noise floor with no subharmonics due to hopping. The proposed regulator hops between two, four, or eight switching frequencies, but chops their phases to fully eliminate spurs, even with only two frequencies. Peaking in the noise floor around the eliminated spurs is minimized by hopping as fast as every switching cycle, and by spacing the frequencies 0.5 MHz apart. This results in less than 1.7% drop in the regulator's efficiency and less than 4 mV increase in the voltage ripple. Implemented in standard 0.35- μm CMOS technology, the proposed regulator's area and power overhead beyond conventional single-switching-frequency design is only 8% and 3%, respectively. With a spur-free spectrum and low noise floor across all frequencies, the proposed architecture can serve as a low-noise regulator for powering noise-sensitive loads without post linear regulation or additional passive filtering. Moreover, spur-free operation facilitates its integration in mixed-signal systems on chip without interfering with sensitive circuits that share the same substrate or power rails. The proposed architecture is also a good candidate for implementing class-D amplifiers, as it preserves the control loop's linearity.
A 40-mA buck regulator operating in the inherently stable Discontinuous Conduction Mode (DCM) for the entire load range is presented. A pulse frequency modulation control scheme is implemented using ...a proposed hysteretic-assisted adaptive minimum-on-time controller to automatically adapt the regulator to a wide range of operating scenarios in terms of input, output, and passive component values while ensuring compensationless DCM operation with minimized inductor peak current. Thus, compact silicon area, low quiescent current, high efficiency, and robust performance across all possible scenarios can be achieved without any calibration. Moreover, power gating is employed in the analog circuits of the proposed controller to further improve efficiency at sub-mA loads. The regulator is integrated within a low-power microcontroller in 90-nm CMOS to power its digital core while allowing maximum flexibility in the powering options of the microcontroller and the choice of the passive components. It occupies 0.1 mm 2 and achieves 92% peak efficiency, and 78.5% and 86% efficiency at 200-μA and 40-mA loads, respectively. It handles an input in the range of 1.8-4.2 V, an output in the range of 0.9-1.4 V, an inductor in the range of 4.7-10 μH, and an output capacitor in the range of 2.2-10 μF without any calibration or reoptimization.
A 1-A 6-MHz buck-boost converter with seamless mode transitions and fast dynamic operation is proposed for extending the useable voltage range of Li-ion batteries in mobile devices, and thereby their ...battery life. The proposed converter employs a proportional-integral peak-current-mode pulsewidth modulation controller with a digital adaptive slew-rate control scheme that minimizes output undershoots, overshoots, and settling time during mode transitions and dynamic events, such as load and output voltage steps. Additionally, hysteretic mode detection is proposed to prevent falsely triggering the converter to transition between the various operation modes (i.e., buck, boost, and buck-boost) and negatively impacting the performance of the circuit loads. The converter is fabricated in 0.13-μm CMOS technology, and supports 2.3-5 V input and 1.5-3.6 V output. The converter achieves 91.7% peak efficiency and over 80% efficiency at 1-mA load across all conditions. The output voltage ripple is less than 10 mV with a 220-nH inductor and a 10-μF output capacitor.
BackgroundAutism spectrum disorder (ASD) is one of the most complex neurodevelopmental disorders. It affects almost all human physiological systems. Individuals with ASD often display dysregulation ...in their autonomic nervous system (ANS), which may elicit differing effects across age groups. Also, studying the ANS missed several important parameters related to ANS. Studying the ANS is crucial in developing adaptive behavioural strategies and maintaining communication abilities and social behaviours. Thus, this study compared the immediate effect of physical activity on the ANS in individuals with ASD in different age groups.Methods200 participants (106 males and 94 females) took part in a double-blinded randomised design. All participants were divided into four groups according to their age (4–7, 7–10, 10–13 and 14–18 years old). Participants performed a 60 min treadmill walk. The main outcome measurements were heart rate (HR), saturation of peripheral oxygen (SpO2), respiratory rate (RR) and end-tidal carbon dioxide (etCO2).ResultsBefore the study, there were non-significant differences between groups in their physical characteristics (body mass index, Childhood Autism Rating Scale, physical activity level, both parents’ existence, aerobic capacity and gender) (p>0.05). At baseline measurements, there were non-significant differences between all groups for all outcome measurements (p>0.05). Immediately after physical activity, there was significant difference between group 1 and other groups (p<0.05), while all other differences were non-significant (p>0.05). At the follow-up (after 15 min of rest), group 1 maintained significant differences with the other groups for all outcome measurements (p<0.05), while there were non-significant differences between the other three groups (p>0.05).ConclusionThis study revealed that the SpO2 significantly decreased immediately after the physical activity, while HR, RR and etCO2 significantly increased immediately after physical activity in comparison to the baseline measurements. Contrary to other ANS parameters (SpO2, RR and etCO2), HR in early ages (4–7 years old) was higher after physical activity and remained elevated longer than other ages. The early ages (4–7 years old) take more time to return to the normal status of ANS parameters including SpO2, HR, RR and etCO2.Trial registration numberNCT05725733.
A commercial off-the-shelf GSM PA powered directly from a DC-DC converter is presented. The converter is implemented in 0.35 μm CMOS and employs frequency hopping with phase chopping to eliminate ...spurious noise. Measurement results demonstrate elimination of spurs, allowing an incompliant GSM PA that is violating the limits of the GSM spectral mask by 9.3 dB to be brought back to compliance without additional filtering or linear regulation between the converter and the PA.
A Maximum Power Point Tracking (MPPT) circuit for a 0.7-W photovoltaic (PV) system is proposed. The circuit employs a modified hill-climbing algorithm based on a 3-points comparison instead of the ...traditional 2-points comparison. The adopted algorithm simplifies the detection of the Maximum Power Point (MPP) and enables the implementation of a periodic sleep-mode to reduce the overall power consumption without compromising effective tracking of irradiance variations. Moreover, to achieve high MPP tracking efficiency, a low-power linear analog multiplier is implemented to accurately compute the instantaneous power of the PV source from its sensed voltage and current levels. This power-metering function is realized in the analog domain to eliminate the need for data converters and to minimize the MPPT circuit's power consumption. A complete design of the proposed circuit is implemented in 0.18-μm BiCMOS process in less than 1.55 mm 2 and consumes less than 25 μW with the digital core running at 500 kHz and a measured peak MPP tracking efficiency of 99.7%.
A current-mode buck regulator with delay-based hysteretic control for microcontroller applications is proposed. Unlike conventional hysteretic buck regulators with accurate explicit hysteretic bands, ...the proposed design relies only on the inherent delay of a low-speed single-threshold comparator to realize the hysteretic band, and can be seamlessly used across all loads in continuous conduction mode and discontinuous conduction mode without modifying the controller's parameters. Moreover, without additional adaptation circuits or frequency regulation loops, the proposed delay-based hysteretic operation does not increase variations in the switching frequency with process and temperature, and results in even less variations in the switching frequency with the input and output voltages when compared to corresponding designs with accurate explicit hysteretic bands. The simplicity of the design reduces silicon area and quiescent current significantly, which in turns enables achieving high efficiency at both heavy and light load conditions as strictly required by low-power microcontrollers. The regulator is designed in a 65 nm digital CMOS technology. It occupies 0.18 mm 2 and supports a wide range of input voltages (1.8-4.2 V), output voltages (0.9-1.5 V), and load current (up to 300 mA). Measurement results show that the proposed regulator achieves 95% peak efficiency, while achieving between 62% and 87% efficiency at 10-μA load across all operating conditions.
APFM-controlled buck converter with discrete frequency hopping is proposed. The converter employs two uniquely related switching frequencies to fully spread the converter's output switching noise ...without generating additional tones at any of the switching frequencies. The peaking in the noise floor resulting from spreading the switching noise is reduced by using up to eight switching frequencies. The converter is implemented in 0.35 μm standard CMOS technology and occupies 0.29 mm 2 . With a spur-free output spectrum and low noise floor peaking, the proposed converter is ideal for low-current noise-sensitive loads such as analog and RF circuit loads in portable communication devices.
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