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Power Management
Published in Nihal Kularatna, DC Power Supplies Power Management and Surge Protection for Power Electronic Systems, 2018
Switched capacitor (charge pump) converters use capacitors rather than inductors or transformers to store and transfer energy. The most compelling advantage is the absence of inductors, which have greater component size, more EMI, greater layout sensitivity, and higher cost. Compared with other types of voltage converters, the switched capacitor converter can provide superior performance in applications that process low-level signals or require low-noise operation. These converters offer extremely low operating current—a useful feature in systems where the load current is either uniformly low or low most of the time. Thus for small handheld products, light-load operating currents can be much more important than full-load efficiency in determining battery life. The basic operation of switched capacitor voltage converters is shown in Figure 6.4 [11].
Switched-Capacitor Circuits
Published in Tertulien Ndjountche, CMOS Analog Integrated Circuits, 2017
Due to the increasing importance of portable systems for data processing in instrumentation and multimedia communication applications, the analog circuitry of modern mixed-signal integrated circuits has to operate with low supply voltage. The use of switched capacitor techniques results in circuits having a high accuracy and a good dynamic range. However, the low supply voltage does not allow a suitable control of the switches whose overdrive is signal dependent (e.g., input switch and switches at the amplifier output). Figure 8.71 shows the on-conductances of a CMOS switch operating with the appropriate and low supply voltages, respectively. By decreasing the supply voltage to about there is a range of the input voltage around VDD/2 for which the nMOS and pMOS transistors will not conduct (see Figure 8.71(b). In the low-voltage circuit design, it is preferable to use either the nMOS or pMOS transistor as a switch. A supply voltage of at least, VT + Voυ, where VT is the transistor threshold voltage and Voυ is the highest voltage level of the signal to be switched, is then required [59].
Design of DC Power Supply and Power Management
Published in Nihal Kularatna, Electronic Circuit Design, 2017
Switched capacitor (charge pump) converters use capacitors rather than inductors or transformers to store and transfer energy. The most compelling advantage is the absence of inductors, which have greater component size, more EMI, greater layout sensitivity, and higher cost. Compared with other types of voltage converters, the switched capacitor converter can provide superior performance in applications that process low-level signals or require low-noise operation. These converters offer extremely low operating current—a useful feature in systems where the load current is either uniformly low or low most of the time. Thus, for small handheld products, light-load operating currents can be much more important than full-load efficiency in determining battery life. The basic operation of switched capacitor voltage converters is shown in Figure 3.46 [134].
Switched-Capacitor phase shifter and topology application for other functions
Published in Australian Journal of Electrical and Electronics Engineering, 2021
From eqns. (4–5), it is clear that the pole frequency can be adjusted by capacitor ratio (CS/C), and the desired phase shifting network design is possible. The design guideline for the circuit is as per the switched-capacitor theory demanding signal frequency to be smaller than the clock frequency for proper sampling of signal. Accurate control over capacitor ratio and clock frequency attribute of switched capacitor circuits, combined with simpler building block and reduced switch count makes the new proposed circuit competitive amongst contemporary filter designs. However, it must be emphasised that circuits characterised by voltage transfer functions necessitate high-input and low-output impedances for easy cascading. The proposed circuit owing to its core being a CCII configured as a current follower would demand voltage follower(s) for embedding with a system for practical usage.
Design and Economic Evaluation of Low Voltage DC Microgrid based on Hydrogen Storage
Published in International Journal of Green Energy, 2021
Mohd Alam, Kuldeep Kumar, Viresh Dutta
Some previous studies are extensively focused on the control and operation of microgrid. Nasirian et al. (2015) have proposed a cooperative control technique to control the operation of the DC microgrid. In this control technique they replaced secondary voltage set point by the voltage and current regulators. This adjustment regulates the microgrid voltage level as required by the tertiary control. Cornea et al. (2017) have given a control strategy for the hybrid DC microgrid. They used a switched capacitor with converters to control the bi-directional power flow in the hybrid microgrid. Switched capacitor application in the converters also provides higher stability and voltage gain. Li et al. (2018) have proposed an observer-based DC voltage droop and feed-forward control for the DC microgrid. Nejabatkhah and Li (2015) presented a review on the power management strategies (droop control, inter-linked converter, and grid-support) of hybrid AC/DC microgrid (ac-coupled, dc-coupled, and ac–dc-coupled). Kwon and Choi (2018) have proposed a control scheme of the bi-directional DC-DC converter for the energy storage system in the microgrid to resolve the issues associated with mode switching. Lu et al. (2015) have demonstrated the integration of the wind generator and wave source generator in the DC microgrid. Mardani et al. (2019) have proposed a model predictive control for the DC-DC converter operation to reduce the effect of pulsed power loads.
A 1.8 V 8.62 µW Inverter-based Gain-boosted OTA with 109.3 dB dc Gain for SC Circuits
Published in IETE Journal of Research, 2019
Yajunath Kaliyath, Tonse Laxminidhi
Switched capacitor circuits are used in the discrete-time implementation of most of the analog and mixed signal integrated circuit (IC) designs such as filters and modulators [1,2]. An OTA is the basic building block in a SC circuit and it accounts for a large fraction of the total power consumed by the IC. Further, the dc gain of an OTA determines the accuracy of charge transfer in the SC circuits [2]. So, SC circuits require an OTA that offers a high dc gain in order to ensure an accurate charge transfer. Folded-cascode topology has been the preferred choice for OTA implementation, as it offers a high dc gain; but, they consume a lot of power when operated at higher supply voltages [3–5]. Recently, inverter-based OTA's have been reported to replace the traditional OTA's in SC applications [6–8]. Design simplicity, area efficiency and power efficiency (at lower supply voltages) are the main advantages of an inverter-based OTA. However, these inverter-based OTA's are suitable for only low voltage applications ( V) because they consume a lot of power when operated at higher supply voltages ( V) [6,8].