Stmicroelectronics Asia Pacific Pte Limited

Teerasak Lee

Yannick Guedon

Supriya Raveendra Hegde

Kien Beng Tan

Baranidharan Karuppusamy

Huiqiao He

Thet Mon Sann

Baris Volkan Yildirim

Chee Weng Cheong

Eng Jye Ng

Disclosed herein is a wireless power reception system that utilizes a switched capacitor DC-DC voltage converter to charge a load. Current sensing circuits described herein enable the measurement of the input current to the switched capacitor DC-DC voltage converter while being relatively insensitive to temperature variation. Voltage/current sensing circuits described herein enable the selective measurement of load voltage, high side load current, and low side load current. One of the current sensing circuits may be used together with one of the voltage/current sensing circuits in a single device, or the current sensing circuits and voltage/current sensing circuits may be used separately in different devices.

Hardware and methods for voltage and current sensing

A wireless power circuit operable in transceiver mode and in Q-factor measurement mode includes a bridge rectifier having first and second inputs coupled to first and second terminals of a coil, and an output coupled to a rectified node. An excitation circuit coupled to the first terminal, in Q-factor measurement mode, drives the coil with a pulsed signal. A protection circuit couples the first terminal to a first node when in Q-factor measurement mode and decouples the first terminal when in transceiver mode. A controller causes the bridge rectifier to short the first and second terminals to ground during Q-factor measurement mode. A sensing circuit amplifies voltage at the first node to produce an output voltage, and in response to the voltage at the first node rising to cross a rising threshold voltage, digitizes the output voltage. The digitized output voltage is used in calculating a Q-factor of the coil.

Foreign objection detection sensing circuit for wireless power transmission systems

A circuit includes a tank capacitor coupled between first and second nodes, and a sense resistor having a first terminal coupled to the first node and a second terminal coupled to a regulator input. A switching circuit has first and second inputs coupled to the first and second terminals of the sense resistor. A gain stage has first and second inputs capacitively coupled to first and second outputs of the switching circuit. An analog-to-digital converter receives the output of the gain stage, and receives first and second differential voltages. A reference voltage generator has a temperature independent current source coupled to source current to a reference resistor, the first differential reference voltage being formed across the reference resistor. The reference resistor and sense resistor are located sufficiently close to one another on a single common substrate such that they remain at substantially a same temperature.

High accuracy low temperature drift high-side current sensing hardware and method

A receiver circuit includes a rectifier operable in full-, half-synchronous and asynchronous modes. A measurement circuit, with method, provides for real-time power measurement within the rectifier. The measurements are made based on the average output current from the rectifier delivered to the load and measurements sampled over time of the instantaneous voltage at each input/output node of the rectifier. Equivalent resistance in the rectifier is determined from the measurements and power dissipation calculated from the determined equivalent resistance and the average output current. The instantaneous voltages are synchronously captured through high-voltage AC coupling in order to detect the voltage drop across each element of the rectifier. The sensed voltages are amplified in the low voltage domain and converted by a high-speed analog-to-digital converter in order to produce data useful in computing equivalent resistance values. From these values, power dissipation within the rectifier is calculated and real-time equivalent resistance is available.

Circuit and method for measuring power dissipation in a rectifier

A bridge rectifier is formed by a first transistor coupled between a regulator output and a first tap, a second transistor coupled between the regulator output and a second tap, a third transistor coupled between the first tap and ground, and a fourth transistor coupled between the second tap and ground. A first comparator circuit, when enabled, compares ground to a voltage at the first tap and asserts a first low-side control signal to turn on the third transistor when the voltage at the first tap is below ground, and, when reset, samples an offset of the first comparator circuit. A second comparator circuit, when enabled, compares ground to a voltage at second first tap and asserts a second low-side control signal to turn on the fourth transistor when the voltage at the second tap is below ground, and, when reset, samples an offset of the second comparator circuit.

Synchronous auto-zero comparator for wireless power rectifier

A wireless-power-transmission-system includes a bridge with a tank-capacitor coupled thereto, a sense-resistor coupled between the bridge and an input of a regulator, a switching-circuit having first and second inputs coupled across the sense-resistor, and a gain-stage having first and second inputs capacitively coupled to first and second outputs of the switching-circuit. An ADC digitizes output of the gain-stage by comparing the output to a reference voltage, and a temperature-independent current source is coupled to a reference-resistor to generate the reference voltage. In a reset-phase, the switching-circuit shorts the inputs of the gain-stage to one another, and the gain-stage shorts its inputs to its output. The switching-circuit, in a first-chopping-phase, couples the sense-resistor between the first and second inputs of the gain-stage, and in a second-chopping-phase, couples the sense-resistor in reverse between the second and first inputs of the gain-stage. The resistance of the reference-resistor tracks the sense-resistor across temperature.

A data demodulating circuit includes a sensing circuit sensing a power signal applied to a coil at first and second times, and outputting an analog value representing a difference in voltage of the power signal at the first and second times. An analog-to-digital converter digitizes the analog value output by the analog voltage differential sensing circuit to produce a digital code. A compensation circuit, over a period of time, compares a present value of the digital code to a first value of the digital code during the period, and subtracts a given value from the present value of the digital code if the present value is greater than the first value but add the given value to the present value of the digital code if the present value is less than the first value. An accumulator accumulates output of the compensation circuit, and a filter filters output of the accumulator.

Adaptive baseline correction for delta amplification

A wireless-power-circuit is operable in transceiver-mode and Q-factor-measurement-mode, and includes a bridge coupled to a coil, and having an output coupled to a rectified-voltage node. An excitation circuit, when in Q-factor-measurement-mode, drives the coil with a pulsed signal. A protection circuit couples the coil to a first node when in Q-factor-measurement-mode and decouples the coil from the first node when in transceiver-mode. A Q-factor sensing circuit includes an amplifier having inputs coupled to the first node and a common mode voltage (Vcm), and generating an output signal having an output voltage. A comparator generates a comparison output indicating Vcm crossing of a voltage at the first terminal of the coil, a processing circuit generating an enable signal based upon the comparison output, and an analog-to-digital-converter, when enabled, digitizing the output voltage for use in calculating a Q-factor of the coil.

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Singapore, Singapore

Teerasak Lee