Hong Kong Applied Science and Technology Research Institute Company, Limited

Ho Ming Karen Wan

Kwok Kuen David Kwong

Yat To William Wong

Chik Wai David Ng

Kwai Chi Chan

Kam Chuen Wan

David Kwok Kuen Kwong

Hok Mo Yau

Chik Wai Ng

Tin Ho Andy Wu

A charge/discharge protection circuit protects a battery from inadvertent shorting on a charger node that can connect to a charger or to a power supply of a portable electronic device. A single n-channel power transistor has a gate that controls a channel between the battery and the charger node. The gate is connected to the charger node by a gate-coupling transistor to turn off the power transistor, providing battery isolation. The gate is driven by a voltage-boosted clock through a switch activated by an enable signal. The enable signal also activates a grounding transistor to ground a gate of the gate-coupling transistor. A comparator compares voltages of the charger and battery nodes, and the compare output is latched to generate the enable signal. An inverse enable signal activates a second switch that drives the voltage-boosted clock to the gate of the gate-coupling transistor to turn off the power transistor.

Single-power-transistor battery-charging circuit using voltage-boosted clock

An error amplifier can be used to control a power regulator transistor. The error amplifier has a main amplifier, a pull-up auxiliary amplifier, and a pull-down auxiliary amplifier that all drive an output. A compensating capacitor on the output sets a single dominant pole for all amplifiers, increasing stability. High slew rates are provided by increased slew current from the auxiliary amplifiers that turn on when the differential input has an absolute voltage difference larger than an intentional offset. The intentional offset is introduced into the auxiliary amplifiers by adjusting a p-channel to n-channel transistor ratio in a leg of the auxiliary amplifiers. A source degenerated resistor in the main amplifier reduces supply headroom and increases linearity by connecting sources of two differential transistors that receive the differential input. Cascode transistors increase gain and output impedance. Reliability is increased as no positive feedback is used in the amplifiers.

Slew-rate-enhanced error amp with adaptive transconductance and single dominant pole shared by main and auxiliary amps

An Analog-to-Digital Converter (ADC) has a Successive-Approximation-Register (SAR) driving a digital-to-analog converter (DAC) that generates an analog voltage compared to an input voltage by a series of stages. The last stage feeds a compare signal to the SAR. Each stage has a dual-input differential amplifier that operates as a unity gain op amp during an auto-zeroing phase and as a high-speed low-gain amplifier during an amplifying phase. The dual-input differential amplifier has two pairs of differential inputs. A secondary pair has an offset-storing capacitor across it, and connects to the output pair through feedback switches during auto-zeroing. A primary pair connects to stage inputs through input switches during the amplifying phase. Since two pairs of differential inputs are provided to the dual-input differential amplifier, the offset capacitor is completely isolated from the input pair. The current sink in the dual-input differential amplifier is adjusted higher during the amplifying period.

Multi-stage comparator with offset canceling capacitor across secondary differential inputs for high-speed low-gain compare and high-gain auto-zeroing

A re-configurable circuit acts as an Analog-to-Digital Converter (ADC) and as a digital-to-analog converter (DAC). An array of binary-weighted capacitors stores an analog input. Switches connect different capacitors in the array to fixed voltages that cause charge-sharing with a terminal capacitor. The voltage of the terminal capacitor is compared by a re-configurable comparator stage for each different combination of the capacitors. The comparison results are analyzed to determine the closest digital value for the analog input. In DAC mode, the array capacitors are switched based on an input digital value. The switched capacitors connect to a charge-sharing line to generate an analog voltage that is applied to the re-configurable comparator stage. A differential amplifier generates a buffered analog voltage that is fed back to the other input of the re-configurable comparator stage for unity gain. The gain of the re-configurable comparator stage adjusts for ADC and DAC modes.

Dual-use comparator/op amp for use as both a successive-approximation ADC and DAC

An oscillator operates at a very low voltage yet has a duty cycle that is set by a ratio of capacitors that are charged and discharged. Sub-threshold p-channel transistors conduct sub-threshold currents below the normal threshold voltage, and drive set and reset inputs of a set-reset S-R latch. The S-R latch drives the oscillator outputs. The oscillator outputs feed back to charging p-channel transistors that charge one plate of the capacitors. During half of the cycle, the charging p-channel transistor is off, allowing one plate of the capacitors to discharge through an n-channel discharge transistor. After a period of discharge determined by the capacitance of the capacitor, the gate of a sub-threshold p-channel transistor falls enough for sub-threshold current to flow, triggering the set or reset input of the S-R latch. Since sub-threshold currents are needed to toggle the S-R latch, the oscillator begins to oscillate below the threshold voltage.

Low-voltage oscillator with capacitor-ratio selectable duty cycle

The fuse cell architecturefor the presently claimed invention employs a multiple fuse structurearchitecture in lieu of a single fuse structure. As such, the terminals of these fuse structures that couple to other on-chip devices are always at ground potential throughout the application of programming voltage to the fuse pads. This approach overcomes previous single fuse problems owing to the fact that a sufficiently high programming voltage can be applied to blow fuse structures with unexpectedly high resistance without damaging nearby on-chip devices. Furthermore, even if one of the fuse structurespossessed an abnormally high resistance which would not be blown under typical conditions, the desired circuit trimming result can still be achieved owing to the blowing of the other fuse structure in the fuse cell

Fuse cell and method for programming the same

A zero-delay clock generator has a phase-locked loop (PLL) that generates a feedback clock and receives a reference clocks. All clocks are differential and have a common-mode voltage. The common-mode voltage of an externally-generated reference clock can vary from the common-mode voltage of the internally-generated feedback clock. Differences in common-mode voltage of the reference clock and feedback clock cause delay variations resulting in static phase offsets of generated clocks. A common-mode sense and equalizer senses the common-mode voltages of the buffered reference and feedback clocks, and generates control voltages. The control voltages adjust the common-mode voltage and delay of differential buffers that receive the reference and feedback clocks. The control voltages adjust the differential buffers to match the common-mode voltages of the buffered reference and feedback clocks. The buffered clocks are then applied to a phase and frequency detector of the PLL.

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Hong Kong, China

Ho Ming Karen Wan