Capacitor Charge Pump Research Articles

An Isolated High Step-Up Converter with Non-Pulsating Input Current for Renewable Energy Applications

This study proposes a novel isolated high step-up galvanic converter, which is suitable for renewable energy applications and integrates a boost converter, a coupled inductor, a charge pump capacitor cell, and an LC snubber. The proposed converter comprises an input inductor and thus features a continuous input current, which extends the life of the renewable energy chip. Furthermore, the proposed converter can achieve a high voltage gain without an extremely large duty cycle and turn ratio of the coupled inductor by using the charge pump capacitor cell. The leakage inductance energy can be recycled to the output capacitor of the boost converter via the LC snubber and then transferred to the output load. As a result, the voltage spike can be suppressed to a low voltage level. Finally, the basic operating principles and experimental results are provided to verify the effectiveness of the proposed converter.

An envelope tracking RF power amplifier with capacitive charge pump modulator

An envelope tracking (ET) radio frequency (RF) power amplifier (PA) is described intended for handsets and applications where a large number of PAs are needed. Instead of the usual split frequency architecture, a linear tracking charge pump structure is proposed. This allows the supply voltage of an RF PA to increase during the peaks of a high peak-to-average power ratio signal. When combined with an LDMOS RF PA, 42.9% efficiency was achieved at 31.3 dBm output power (POUT) when amplifying a 5 MHz bandwidth 8 dB PAPR 3rd Generation Partnership Project (3GPP) long term evolution signal. The first channel adjacent power ratio (ACPR) without digital pre-distortion was −30.4 dBc, meeting the 3GPP handset emission mask. The ACPR could be improved to −32.5 dBc by adopting a curved envelope shaping function at a reduced efficiency of 38.9%.

Dynamic joint model of capacitive charge pumps and on‐chip photovoltaic cells for CMOS micro‐energy harvesting

SummaryOn‐chip energy harvesting by means of integrated photovoltaic cells in standard CMOS technology can be successfully used to recharge or power‐up integrated circuits with the use of charge pumps for voltage boosting. In this paper, a tool to facilitate the design of such structures is proposed consisting of an accurate model of the joint dynamics of the micro‐photovoltaic cell and a capacitive DC/DC converter in the slow‐switching limit regime. The model takes into account both the top and bottom parasitic capacitances of the flying capacitors. We assume a classical model for the photodiode whose photogenerated current is extracted from device‐level simulations. The joint model is verified by circuit‐level simulations achieving high accuracy and computation time savings of up to 1700×. The joint model shows that the voltage generated by an integrated photovoltaic cell connected to a capacitive DC/DC converter is not constant even under constant illumination. This phenomenon can only be reproduced through the joint model and failing to take it into account results in an error in the estimation of the time needed by the DC/DC converter to reach a given output voltage. We also demonstrate that the maximum output voltage reached by a DC/DC converter in the slow‐switching limit regime when a photovoltaic cell is used as energy transducer depends on the switching frequency. Finally, the applicability of the model is illustrated through the optimization of time response and charge efficiency for the Dickson, Fibonacci, and exponential topologies in the case of implantable devices. Copyright © 2016 John Wiley & Sons, Ltd.

One Cycle Contol of High Gain Boost Converter with Coupled Inductor and Charge Pump Capacitor

One Cycle Contol of High Gain Boost Converter with Coupled Inductor and Charge Pump Capacitor

Variable-Form Carrier-Based PWM for Boost-Voltage Motor Driver With a Charge-Pump Circuit

A boost-voltage motor driver with a charge pump (CP) circuit has higher efficiency than the conventional boost-voltage motor driver with a chopper circuit. This paper presents a variable-form carrier-based (VFCB) pulsewidth modulation (PWM) technique for the driver with the CP circuit. This technique has two triangular carriers and a variable-form carrier that is dependent on the voltage command signals. The technique is compared with the space vector modulation (SVM) technique in terms of the number of switching cycles, harmonics in the output voltage, linear modulation range, input power to the CP capacitor, processing time, and efficiency. The VFCB PWM technique is confirmed to operate the driver with the CP circuit at the same performance level as the SVM technique, with shortened processing time.

Electrostatic converter with an electret-like elastomer membrane for large scale energy harvesting of low density energy sources

Low density energy sources, like wind and solar energy, are widely available and they are increasingly used for electricity conversion worldwide. Ambient energy sources with even lower energy densities are universally available and could equally be converted into electricity with large scale special purpose converter systems. This work discusses a simple concept for an electret-based electrostatic converter suitable for large scale conversion of ambient low density energy sources. The converter is a capacitive charge pump capable of working at low frequencies (≤1Hz) with a very low mechanical input energy and a high conversion efficiency. With a charged electret-like elastomer membrane the converter can operate without an initial bias voltage supply. First tests with a simple proof-of-concept demonstrator resulted in a mechanical input energy of 332 μJ (9.1 μJ/cm2) and a converted electrical output energy of 206 μJ (5.7 μJ/cm2) per conversion cycle. This gives a total conversion efficiency of 63%.

High Step-Up Converter with Hybrid Structure Based on One Switch

A novel high step-up converter is presented herein, which combines the conventional buck-boost converter, the charge pump capacitor and the coupling inductor. By doing so, a quite high voltage conversion ratio due to not only the turns ratio but also the duty cycle, so as to increase design feasibility. It is noted that the denominator of the voltage conversion ratio is the square of one minus duty cycle. Above all, there is no voltage spike across the switch due to the leakage inductance and hence no passive or active snubber is needed, and furthermore, the used switch is driven without isolation and hence the gate driving circuit is relatively simple, thereby upgrading the industrial application capability of this converter. In this paper, the basic operating principles and the associated mathematical deductions are firstly described in detail, and finally some experimental results are provided to demonstrate the effectiveness of the proposed high step-up converter.

Improved KY Converter

In this paper, an improved KY converter is presented, which is constructed mainly by one charge pump capacitor and one central-tapped coupling inductor. Besides, a passive clamping snubber is added to this converter to improve the efficiency above half load. As compared to the KY converter, the voltage conversion ratio of the proposed converter is upgraded significantly. In this paper, the basic operating principles and mathematical deductions of the proposed converter are described, along with some experimental results provided to demonstrate the feasibility and effectiveness of the proposed converter.

Eliminating hysteresis of piezoelectric deformable mirror by charge control

Inherent hysteresis of piezoelectric deformable mirror (DM) limits the performance of adaptive optics (AO) systems including bandwidth and residual wavefront error. A charge control method based on switched capacitor charge pump was proposed to eliminate the hysteresis of piezoelectric DM. Experimental results show that the hysteresis of a unimorph DM was reduced from 11% to less than 1%. It indicates that the proposed charge control method has the potential to improve the deformation precision for one step correction as well as the bandwidth of the AO systems.

Switched capacitor charge pump used for low-distortion imaging in atomic force microscope.

The switched capacitor charge pump (SCCP) is an effective method of linearizing charges on piezoelectric actuators and therefore constitute a significant approach to nano-positioning. In this work, it was for the first time implemented in an atomic force microscope for low-distortion imaging. Experimental results showed that the image quality was improved evidently under the SCCP drive compared with that under traditional linear voltage drive.

A high step-up and low switches voltage stress boost converter

To increase the output voltage range efficiently in distributed generation system, a novel high step-up and low switches voltage stress boost converter with charge pump capacitor is proposed in this paper. The structure and basic operating principles analysis are provided, but also the results of the analysis are verified by simulation and experiment.

A Low-Voltage Low-Power Opamp-Less 8-bit 1-MS/s Pipelined ADC in 90-nm CMOS Technology

This paper presents an 8-bit pipelined analog-to-digital converter. The supply voltage applied for comparators and other sub-blocks of the ADC were 0.7V and 0.5V, respectively. This low power ADC utilizes the capacitive charge pump technique combined with a source-follower and calibration to resolve the need for the opamp. The differential charge pump technique does not require any common mode feedback circuit. The entire structure of the ADC is based on fully dynamic circuits that enable the design of a very low power ADC. The ADC was designed to operate at 1MS/s in 90nm CMOS process, where simulated results using ADS2011 show the peak SNDR and SFDR of the ADC to be 47.8 dB (7.64 ENOB) and 59 dB respectively. The ADC consumes less than 1mW for all active dynamic and digital circuitries.

New fully-differential amplifier-less pipelined ADC with wide power scalability and ERBW

A new fully-differential energy-efficient amplifier-less technique for pipelined analog-to-digital converter (ADC) suitable for video signal conversion is presented in this paper. It employs a capacitive charge pump and a comparator-controlled charging buffer to realize the residue amplification. The circuit is differential and the common-mode input is rejected at the output, although no active common-mode feedback circuit is used. In principle, this technique eliminates static power consumption in the residue amplification process, leaving only the necessary dynamic power consumption, which is directly scalable to the sampling rate (f s ) like in a digital circuit. A prototype ADC was fabricated in a 1.8 V 0.18 µm CMOS technology. It consumes 54 µW at 125 kS/s and 4.94 mW at 25 MS/s while measuring a signal-to-noise-plus-distortion ratio of 52 dB, independent of f s . Furthermore, enabled by a built-in passive sample-and-hold, the ADC achieves a 36 MHz effective resolution bandwidth at 25 MS/s.

High‐voltage‐boosting converter with charge pump capacitor and coupling inductor combined with buck–boost converter

A novel high-voltage-boosting converter is presented herein, which combines the traditional buck-boost converter, the charge pump capacitor and the coupling inductor. By doing so, the proposed converter possesses a high-voltage conversion ratio, which can be obtained based on not only the duty cycle, but also the turn ratio so as to increase design feasibility. Above all, the used switch is driven without isolation and hence the gate driving circuit is relatively simple, thereby upgrading the industrial application capability of this converter. In this study, the basic operating principles and the associated mathematical deductions are firstly described in detail, and finally some experimental results are provided to demonstrate the effectiveness of the proposed high-voltage-boosting converter.

Investigation of Supply Current Spikes in Flash Memories Using Ion-Electron Emission Microscopy

We studied the occurrence of supply current spikes and destructive events in NAND flash memories under heavy-ion exposure. In addition to broad-beam experiments, we used collimated beams and ion-electron emission microscopy to investigate the phenomena on two types of memories with different feature size. Current spikes on the supply current were observed in both devices, also with collimated beams, whereas destructive events occurred only with broad beam. We show that current spikes do not originate from charge-pump capacitors, as previously suggested, and propose that destructive events are due to the effects of temporally close heavy-ion hits on distinct areas of the tested chips.

31.2: Power Efficient 5.0‐inch 440ppi Full HD a‐Si TFT LCD Single‐Chip Driver IC

AbstractWe have developed the single chip driver system for 5.0‐inch 1080RGBx1920 FHD with 440ppi a‐Si TFT LCD panel for high‐end smart phone applications. Capacitive Charge‐Pump and inductive PFM (Pulse Frequency Modulated) combined new type of DC‐DC converter architecture has been proposed for the GIP (Gate Circuits In the Panel) turning on/off powers, or VGH and VGL, to develop successful and power efficient single chip driver IC. The measured results show that the proposed combined DC‐DC converter has the merits of stable and over 23% power saving effect in comparison with the conventional capacitive Charge‐Pump only or inductive PFM only DC‐DC converters, respectively.

Leakage current characterization and compensation for piezoelectric actuator with charge drive

In this paper, the effects of leakage current on piezoelectric actuators with charge drive are presented, and a method to compensate it is proposed. Considering a piezoelectric stack driven by a switched capacitor charge pump as an example, the leakage current was found to be dependent on the voltage applied on the actuator but had a negligible relationship with the driving routes. The nonlinear relationship between the leakage current and the voltage was investigated, and a feedback circuit based on the applied voltage of the actuator was used for compensation. Experimental results showed that a displacement drift rate of lower than 0.033nm/s could be achieved with an applied voltage from 0V to 60V, whereas the drift rate was as large as 0.9nm/s without compensation.

A Low-Power Delta-Sigma Modulator Using a Charge-Pump Integrator

In this paper a low-power switched-capacitor integrator based on a capacitive charge-pump (CP) is presented, and its practical effects are discussed. The CP integrator is employed as the first stage of a ΔΣ ADC. The 0.13 μm CMOS prototype of the CP based ADC achieves the same performance as a conventional ADC while consuming 66% lower OTA power in the front-end integrator. The CP based modulator realizes 87.8 dB SNDR, 89.2 dB SNR and 90 dB DR over a 10 kHz bandwidth with 148 W power consumption. The conventional ADC has similar performance but dissipates 241 W. The energy required per conversion-step for the CP based ADC (0.369 pJ/step) is almost 40% lower than that of the conventional ADC (0.607 pJ/step).

A novel low ripple charge pump with a 2X/1.5X booster for PCM

A low ripple switched capacitor charge pump applicable to phase change memory (PCM) is presented. For high power efficiency, the selected charge pump topology can automatically change the power conversion ratio between 2X/1.5X modes with the input voltage. For a low output ripple, a novel operation mode is used. Compared with the conventional switched capacitor charge pump, the flying capacitor of the proposed charge pump is charged to Vo − Vin during the charge phase (Vo is the prospective output voltage). In the discharge phase, the flying capacitor is placed in series with the Vin to transfer energy to the output, so the output voltage is regulated at Vo. A simulation was implemented for a DC input range of 1.6–2.1 V in on SMIC standard 40 nm CMOS process, the result shows that the new operation mode could regulate the output of about 2.5 V with a load condition from 0 to 10 mA, and the ripple voltage is lower than 4 mV. The maximum power efficiency reaches 91%.

Development of Discrete Power Supply with Charge Pump Method for High Powered Sonar System

Power supply is one of the electronic devices that can provide electric energy for electronic systems or other systems. There are several types of power supplies that can be applied depend on the requirement and functions. One example is the use of power supply for sonar systems. Sonar system is a device which can be used to detect a target under water. The sonar system is an electronic circuit that requires a power supply with specific characteristics when the sonar functions as a transmitter and a receiver in the specific span time (when on) and the specific lag time (when off). This paper discusses the design of power supply for high-powered sonar systems with discrete methods in which high power supply is only applied when the acoustic waves radiated under water. Charge pump was used to get the appropriate output voltage from lower input voltage. Charge pump utilized a combination of series and parallel connections of capacitors. The working mode of this power supply used the lag time as the calculation of time to charge charge pump capacitors in parallel while the span time was used for the calculation of discharging the charge pump capacitors in series.