Chun-Yu Hsieh

A Li-Ion Battery Charger With Smooth Control Circuit and Built-In Resistance Compensator for Achieving Stable and Fast Charging

A built-in resistance compensator (BRC) technique is presented to speed up the charging time of a lithium-ion battery. A smooth control circuit (SCC) is proposed to ensure the stable transition from the constant-current (CC) to the constant-voltage (CV) stage. Due to the external parasitic resistance of the Li-ion battery-pack system, the charger circuit switches from the CC to the CV stage without fully charging the cell. The BRC technique dynamically estimates the external resistance to extend the CC stage. The experimental results show that the period of the CC stage can be extended to 40% of that of the original design. The charging time is effectively reduced.

Highly Efficient Analog Maximum Power Point Tracking (AMPPT) in a Photovoltaic System

A compact-size analog maximum power point tracking (AMPPT) technique is proposed in this paper for high power efficiency in the photovoltaic (PV) system. Combining existing MPPT approaches, we present a fast and accurate tracking performance. Here, a wide-range current multiplier, which tracks the maximum power point (MPP) in the solar power system, is implemented to detect the power slope condition of the solar panel. Experimental results show that the proposed technique can rapidly track the MPP with a high tracking accuracy of 97.3%. Furthermore, the proposed system can connect to the grid-connected inverter to supply ac power.

A DVS embedded power management for high efficiency integrated SOC in UWB system

The proposed power management module with a typical 1.2 V low-voltage PWM (LV-PWM) controller and dynamic voltage scaling (DVS) function is designed using 65 nm technology for integration with the ultra-wide band (UWB) system. The on-chip pre-regulator with a power conditioning circuit can provide a regulated supply voltage to the LV-controller. Moreover, the proposed handover technique can achieve the self-biasing mechanism to further reduce power dissipation. To operate in low voltage, the proposed compensation enhancement multistage amplifier (CEMA) can achieve high loop gain and ensure system stability without using any external compensation component. The fabricated power management module occupies 0.356 mm2 silicon area with an excellent line/load transient response. Owing to the DVS function, the proposed power management can meet the power requirement in the UWB system and other RF transceiver systems.

Adaptive Droop Resistance Technique for Adaptive Voltage Positioning in Boost DC–DC Converters

In this paper, an adaptive droop resistance (ADR) technique can compensate for the adaptive voltage positioning (AVP) control in a boost dc-dc converter. A loop analysis is derived with the AVP technique to show the effects of the right-half-plane (RHP) zero. When the value of RHP zero is above the equivalent series resistance (ESR) zero, constant output impedance can be guaranteed by the proposed compensation method. Once the value of RHP zero is below five times of ESR zero, the proposed ADR technique can vary the droop resistance to track the variation of the load current to increase the system stability. In case of load current variation, the output impedance is proven constant due to the implementation of the AVP technique in the boost converter. The transient response time is 22 μS when a 200-mA load current step occurs, which is faster than that of a conventional boost converter. Even at heavy loads, the ADR technique can ensure a fast and stable transient response without being affected by the RHP zero. The experimental results demonstrate that the proposed method can increase system stability and guarantee a fast transient response in the design of a boost converter with the AVP technique.

A Battery-Free 217 nW Static Control Power Buck Converter for Wireless RF Energy Harvesting With

A battery-free nano-power buck converter with a proposed dynamic on/off time (DOOT) control can achieve high conversion efficiency over a wide load range. The DOOT control can predict the on/off time at different input voltages without a power consuming zero current detection (ZCD) circuit, as well as suppress static power in idle periods. To adapt to the fluctuations in a harvesting system, the proposed α-calibration scheme guarantees accurate ZCD over process, voltage variation, and temperature (PVT) in the DOOT to improve power conversion efficiency. Furthermore, the adaptive phase lead (APL) mechanism can improve inherent propagation delay attributable to low-power and non-ideal comparator, thus improving load regulation by a maximum of 30 mV. The test chip was implemented in 0.25-μm CMOS process with a die area of 0.39 mm2. Experimental results showed 95% peak efficiency, low static power of 217 nW and good load regulation of 0.1 mV/mA, which are suitable for RF energy harvesting applications.

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The proposed low-dropout (LDO) regulator with a smooth peak current control (SPCC) circuit can be simultaneously controlled by using an error amplifier to regulate output voltage and a peak current controller as a means to limit its current level. The SPCC circuit can be switched smoothly between these two control mechanisms by detecting the information of load current and the dropout voltage. Measured results show that overcurrent protection can make the pass device operate as a current source while the load current exceed the peak current level. Moreover, the control mechanism can return to error amplifier control when load current becomes smaller than the limiting current, thus ensuring output voltage to be close to the rated value. Output voltage is stable and varies smaller than 15 mV when a 160 mA load current step or a 2 V supply voltage step is placed on this LDO regulator.

-Calibrated Dynamic On/Off Time and Adaptive Phase Lead Control

A load dependent proportional-integration (PI) compensation is proposed in this paper for minimizing transient dropout voltage and accelerating the transient response of current mode DC-DC converters. The adaptive compensation resistance and capacitance are used to react to the sudden load variations: At the beginning of load transient response, the adaptive compensation capacitance is decreased to move the compensation pole-zero pair to a higher frequency for achieving fast transient response. At the end of load transient response, the pole-zero pair is moved back to an optimal position for extending the system bandwidth and phase margin based on the instant load condition. Simulation results demonstrate the excellent performance at transient period and steady-state with this proposed fast transient control and adaptive pole-zero compensation. The overshoot/undershoot voltage is smaller than 45mV and transient period is shorter than 15us as load current suddenly changes between 100mA and 500mA.

A Low-Dropout Regulator With Smooth Peak Current Control Topology for Overcurrent Protection

A trade-off performance between static error and dynamic response is made by the combination of proportional (P) and proportional derivative (PD) compensations. Owing to the fast transient response provided by the P compensator, the static error is also reduced by the PD compensator within a reasonable response time. The proposed control circuit is entirely implemented by voltage mode and has better line and load regulations. An asynchronous 1.8MHz DC/DC boost converter was fabricated by UMC 0.35mum to generate 35V output voltage to turn on more than 10 LED at the same time for the notebooks backlight.

Current mode DC-DC buck converters with optimal fast-transient control

An ultra low-power, precise voltage reference using a switched-capacitor technique in 0.35-μm CMOS is presented in this paper. The temperature dependence of the carrier mobility and channel length modulation effect can be effectively minimized by using 3.3 and 5 V N-type transistors to operate in the saturation and subthreshold regions, respectively. In place of resistors, a precise reference voltage with flexible trimming capability is achieved by using capacitors. When the supply voltage is 1 V and the temperature is 80°C, the supply current is 250 nA. The line sensitivity is 0.76%/V; the PSRR is -41 dB at 100 Hz and -17 dB at 10 MHz. Moreover, the occupied die area is 0.049 mm2.

LED drivers with PPD compensation for achieving fast transient response

A low cost analog MPPT technique is proposed in this paper for high power efficiency in photovoltaic systems. A wide-range current multiplier, which tracks the maximum power point (MPP) in the solar system, is implemented to detect the power slope condition of solar panels. Experiment results show the proposed technique can rapidly track the MPP with a high tracking effectiveness of 97.3%. Furthermore, the proposed system can supply a grid-connected inverter for providing AC power.