The Hong Kong University of Science and Technology

Kwok Tai Philip Mok

Ka Nang Leung

Wing Hung Ki

Kin On Johnny Sin

Hoi Lee

Xiaocheng Jing

Chulwoo Kim

Jungmoon Kim

Fan Yang

Tsz Yin Man

Man Sun John Chan

Ying Wu

Man Siu

Sai Kit Lau

Ka Chun Kwok

Yip Sum Tsui

A digital linear voltage regulator includes a power stage (), arranged in a hierarchical grouping of power stage units. The power stage () is configured to deliver power to a load (). The digital linear voltage regulator further includes a mixed-signal controller (), configured to control each power stage unit in the power stage () by conditionally adjust a number of active power stage units in the power stage () based on a comparison of a feedback voltage of the load () and a reference voltage; wherein the hierarchical grouping of power stage units comprises N levels; wherein the power stage () comprises a number of MNth level units, and an Nth level unit comprising a number of M(N&#x2212;1)th level units; and wherein N is an integer greater than or equal to 3, and Mand Mare integers greater than or equal to 1.

Three-dimensional power stage and adaptive pipeline control

A charge pump (CP) that operates at low input voltage with high power conversion efficiency is disclosed. A first embodiment provides a negative CP used for controlling load switches of a voltage doubler. Using a negative CP extends the operating region below ground to relieve the power delivery limitation of the CP. A second embodiment provides a low power adaptive dead-time circuit, which has several dead-time signals having different lengths of dead-times and selects one according to the input voltage level. A low input voltage detector in the adaptive dead-time circuit is used to determine which dead-time should be used. A third embodiment provides a switching body bias used for the low input voltage CP. The switching body bias uses both forward and reverse body bias applied to the CP to minimize reverse current and maximize power transfer. The first, second, and third embodiments can be used together or independently.

Charge pumping apparatus for low voltage and high efficiency operation

A single-inductor-multiple-output (SIMO) DC-DC switching regulator with a current-mode hysteretic control technique having an ultra-fast transient response to suppress cross-regulation is provided. The DC-DC switching regulator includes: at least one power source for providing electrical energy; an inductive energy storage element for accumulating and transferring the electrical energy from the input power source to a plurality of outputs; a main switch for controlling energy accumulation at the inductive energy storage element; a plurality of output switches for controlling energy transfer to each of the plurality of outputs; a freewheel switch coupled in parallel with the inductive energy storage element; and a controller, configured to coordinate the plurality of output switches and the main switch.

Single-inductor-multiple-output regulator with synchronized current mode hysteretic control

A frequency-hopping pulse-width modulator is disclosed, which facilitates a switching regulator to use smaller-size inductive and capacitive elements, to have an improved power efficiency at light load, as well as predictable spectrum at different load levels. The improved modulator automatically determines the switching frequency of a switching regulator according to the load current delivered by the switching regulator from a number of pre-defined frequencies, which are all multiples of a fundamental frequency. By designing the maximum switching frequency of frequency-hopping pulse-width modulator in the MHz range, a switching regulator is able to use smaller-size inductive and capacitive elements. Light-load efficiency of the switching regulator with the frequency-hopping pulse-width modulator is also greatly improved as switching frequency of such switching regulator is reduced with decreased load current. More importantly, spectrum of a switching regulator with the frequency-hopping pulse-width modulator is as predictable as spectrum of a switching regulator with a conventional pulse-width modulator operated at the fundamental frequency.

Frequency-hopping pulse-width modulator for switching regulators

A switching regulator is provided herein comprising a voltage source, a plurality of switching elements, an inductive element, and a controller. The controller coordinates the plurality of switching elements as to sequentially and periodically switching the inductive element to generate a plurality of regulated DC voltages. The controller adjusts a switching frequency of the regulator in accordance with at least one characteristic of a load current.

Single-inductor-multiple-output regulator with auto-hopping control and the method of use

A frequency compensation method for voltage-mode switching regulators is disclosed. A lowpass filter and a bandpass filter are employed in the two signal paths into the dual inputs of PWM comparators. In one embodiment, two zeros are generated to compensate for the L-C output filter poles. Stable operation, low output voltage ripple and fast load transient response are achieved; while the power consumption of error amplifier and the area for implementing on-chip passive components are greatly reduced.

Frequency compensation based on dual signal paths for voltage-mode switching regulators

A low-dropout regulator comprises a high-gain error amplifier having a differential input stage and a single-ended output, a high-swing high-positive-gain second stage with input connecting to the output of the error amplifier and a single-ended output, a p-type MOS transistor with gate terminal connecting to the output of the second stage, source terminal connecting to the supply voltage, and drain terminal to the output of the low-dropout regulator. A first-order high-pass feedback network connects the output of the low-dropout regulator and the positive input of the error amplifier, and a damping-factor-control means comprising a negative gain stage with a feedback capacitor connects the input and output of this gain stage. A capacitor is connected between the output of the error amplifier and the output of the low-dropout regulator, while a voltage reference connects to the negative input of the error amplifier. The regulator does not require an off-chip capacitor for stability and has improved load transient response and power supply rejection ratio.

Low dropout regulator capable of on-chip implementation

A switched-capacitor regulator is provided for regulating the output voltage of a voltage supply. The switched-capacitor regulator includes a supply input terminal capable of receiving a supply voltage, two or more flying capacitors, a regulation switch located between each flying capacitor and the supply input terminal, and a voltage control circuit. The activity of the regulation switches is controlled by the voltage control circuit. In one embodiment of the invention, the voltage control circuit includes a feedback resistance area having one or more feedback resistors located between the output of the flying capacitors and a ground terminal, a first gain stage connected to the feedback resistance area, and two or more second switchable gain stages, which are each connected to a regulation switch and the first gain stage. The switched-capacitor regulator operates in pseudo-continuous regulator mode using three-stage switchable operational amplifiers with time-multiplexed pole-splitting compensation.

Switched-capacitor regulators

An End-Point Prediction scheme is described for voltage-mode buck regulators to generate adaptive output voltage to integrated-circuit systems. Internal nodal voltages of the regulator controller are predicted and set automatically by the proposed algorithms and circuits. The settling time of the regulator can therefore be significantly reduced for faster dynamic responses, even with dominant-pole compensation.

End-point prediction scheme for voltage regulators

An area-efficient capacitor-free low-dropout regulator based on a current-feedback frequency compensation technique is disclosed. An implementation of a current feedback block with a single compensation capacitor is used to enable capacitance reduction. The resultant low-dropout regulator does not generally require an off-chip capacitor for stability and is particularly useful for system-on-chip applications.

Area-efficient capacitor-free low-dropout regulator

A CMOS reference voltage generating circuit is described that produces a reference voltage by taking the difference between the gate-source voltages of two p-type and n-type CMOS transistors operating in the saturation region, one of the gate-source voltages being multiplied by a gain factor. Different circuits are described for situations where the n- or p-type transistors have the greater temperature dependence.

CMOS voltage reference

A three stage amplifier is disclosed provided with a novel frequency compensation technique. Only a single feedback loop with a single compensation capacitance is provided. Instead of a conventional nested compensation technique, damping factor control is provided by means of a fourth gain stage in order to stabilize the amplifier. The resulting amplifier is particularly useful to drive large capacitive loads for low-voltage low-power applications.

Frequency compensation techniques for low-power multistage amplifiers

A method and apparatus are disclosed for the dimming control of a fluorescent lamp driven by an electronic ballast. A small portion (eg less than 15&deg;) of the phase of the input supply voltage is removed, and the precise amount of the phase removed is used to generate a switching signal that controls the switching frequency of the electronic ballast and hence the light power output. The switching frequency is generated by producing pulses of a width proportional to the amount of phase removed, integrating the pulses to produce a voltage proportional to the phase removed, converting that voltage to a current that varies with a frequency depending on the voltage, and using that varying current to generate the switching frequency.

Growing community of inventors

Hong Kong, China

Kwok Tai Philip Mok