Abstract: A wireless device includes an energy harvester to convert harvested energy into a harvested voltage, a first port selectively connected to an external USB power source, a second port selectively connected to a battery, a load including a plurality of circuits, and a power management circuit coupled to the energy harvester, the first and second ports, and the load. The power management circuit includes a controller configured to select one of the energy harvester, the USB power source, or the battery as a power source at system startup based on one or more of an amount of the harvested voltage, a presence of a connection with the USB power source, a presence of a connection with the battery, or an amount of charge or voltage stored by the battery. The power management circuit also includes a switcher matrix to power the load at system startup using the selected power source.

Abstract: A wireless device includes an energy harvester configured to convert energy harvested from radio-frequency (RF) signals into a harvested voltage, a storage capacitor to store a voltage, a first port selectively connected to an external USB power source, a second port connected to a battery, a load including a non-volatile memory storing configuration data indicating a plurality of charging configurations, and a power management circuit including a controller and a switcher matrix. The controller is configured to select one of the plurality of charging configurations based on one or more of a presence of a connection with the external USB power source, a type of the battery, an amount of the harvested voltage, or a level of the voltage stored on the storage capacitor. The switcher matrix is configured to charge the battery based on the selected charging configuration.

Abstract: A wireless device that can save and restore state information is disclosed. The wireless device stores state information in non-persistent registers during an active power state, routes the state information from the non-persistent registers to a non-volatile memory, via a boundary scan chain using one or more test signals, based on an indication that the wireless device is to enter a low-power state, and enters the low-power state after the state information is stored in the non-volatile memory. The wireless device may remove power from the processor, the non-persistent registers, the non-volatile memory, and one or more other portions of the wireless device during the low-power state. The wireless device may return to the active power state after a period of time and restore the state information to the non-persistent registers upon returning to the active power state.

Abstract: A programmable ring oscillator for a wireless device is disclosed. The programmable ring oscillator includes a Schmitt trigger, first and second CMOS inverters, first and second resistors, and a capacitor. The Schmitt trigger includes an input coupled to a first node, a control terminal coupled to a configuration signal, and an output. The first CMOS inverter includes an input coupled to the output of the Schmitt trigger and an output coupled to a second node. The second CMOS inverter includes an input coupled to the second node and an output coupled to an output terminal configured to provide an output signal having a oscillating frequency. The first resistor is coupled between the output terminal and a third node, and the second resistor is coupled between the third node and the first node. The capacitor is coupled between the second node and the third node.

Abstract: Systems and methods for energy harvesting are disclosed. An example method is performed by a computing device coupled to an energy harvesting circuit and includes identifying a first time period required for the energy harvesting circuit to complete a first number of energy extraction events, the first time associated with an initial harvest voltage, determining a first value of an estimated extracted power based on the initial harvest voltage and the first number of energy extraction events, and iteratively adjusting the harvest voltage and determining the optimal harvest voltage based at least in part on values of the estimated extracted power value corresponding to the adjusted harvest voltage.

Abstract: An IoT device includes a serial interface controller coupled to external sensors, a Bluetooth controller to transmit signals over a Bluetooth connection, a microprocessor, and a sensor hub that controls operations of the serial interface controller and the Bluetooth controller. The microprocessor is initialized to a normal power state and, in response to a first trigger, is placed in a low-power state during which some operations, including at least including polling the sensors for data, are delegated from the microprocessor to the sensor hub. In this way, the microprocessor can sleep or hibernate, thereby reducing power consumption. The microprocessor is returned to the normal power state in response to a second trigger, and responsibility for the delegated operations returns to the microprocessor. The delegated operations may also include storing the polled sensor data in memory and/or facilitating transmission of the sensor data to a host device over the Bluetooth connection.

Abstract: Methods and apparatus for baseband receiver circuits are disclosed. An example receiver circuit includes a first amplifier stage to receive input signals and generate intermediate signals responsive to the one or more input signals and based at least in part on one or more amplifiers, one or more capacitors, and one or more resistors of the first amplifier stage, a second amplifier stage to receive the intermediate signals and generate output signals responsive to the one or more intermediate signals based at least in part on one or more amplifiers, one or more capacitors, and one or more resistors of the second amplifier stage, and calibration logic configured to disconnect the first amplifier stage from the second amplifier stage, inject one or more first signals into at least the first amplifier stage and calibrate at least the first amplifier stage based at least in part on a frequency response of the first amplifier stage to the injected one or more first signals.

Abstract: A method for powering a wireless device includes determining a presence or absence of a USB power source connected to the wireless device, determining a presence or absence of a battery connected to the wireless device, obtaining a level of energy harvested from a surrounding environment of the wireless device, and powering a load of the wireless device using one of the USB power source, the battery, or the harvested energy based on the presence or absence of the USB power source, the presence or absence of the battery, and the harvested energy level.

Abstract: This disclosure provides methods, devices, and systems for operational amplifier frequency compensation. The present implementations more specifically relate to techniques for dynamically calibrating the capacitance of a compensation capacitor based on the frequency at which an operational amplifier oscillates. In some aspects, an operational amplifier may include a differential input stage, a high gain stage, and a frequency compensation controller configured to operate the operational amplifier in a normal mode or a calibration mode. Compensation capacitors are switchably coupled between the outputs of the differential input stage and the outputs of the high gain stage based on the operating mode of the operational amplifier. More specifically, in the calibration mode, the coupling of the capacitors causes an output voltage of the op amp to oscillate relative to an input voltage. By contrast, in the normal mode, the coupling of the capacitors causes the output voltage to track the input voltage.

Abstract: A wireless device includes an energy harvester to convert harvested energy into a harvested voltage, a first port selectively connected to an external USB power source, a second port selectively connected to a battery, a load including a plurality of circuits, and a power management circuit coupled to the energy harvester, the first and second ports, and the load. The power management circuit includes a controller configured to select one of the energy harvester, the USB power source, or the battery as a power source at system startup based on one or more of an amount of the harvested voltage, a presence of a connection with the USB power source, a presence of a connection with the battery, or an amount of charge or voltage stored by the battery. The power management circuit also includes a switcher matrix to power the load at system startup using the selected power source.

Abstract: Implementations are disclosed for controlling a discontinuous mode power switching regulator to avoid specific switching frequencies by the regulator that may cause interference. A controller may be configured to operate in different modes to cause the switching regulator to energize and dump the inductor at different rates based on a frequency of requests to energize the inductor. The controller is to receive a plurality of requests to energize the inductor and generate a control signal based on the plurality of requests (with the control signal causing a first number of switching events at the switching regulator over a defined time period). The controller is to also determine whether a switching frequency of the switching regulator is an undesired switching frequency and switch from the first mode to a second mode (with the control signal generated while in the second mode causing the switching frequency of the switching regulator to change).

Abstract: Implementations are disclosed for a power switching regulator defined to be used for power harvesting but is instead configured to include an additional power rail. A switching regulator includes a first contact defined as a first power input to the switching regulator (with the first contact coupled to a first power source), a second contact defined as a second power input to the switching regulator (with the second contact defined to be coupled to a harvester), and a third contact whose output is defined as a storage voltage for harvesting. Instead of the third contact being used for outputting a storage voltage for harvesting, the third contact is coupled to a voltage (VSTORE) power rail for providing power (that may be configurable) to one or more electronic components of the electronic device (such as a CPU to perform dynamic voltage scaling or by a power amplifier sensitive to power efficiency).

Abstract: A wireless device includes one or more transmit chains configured to upconvert signals from a baseband frequency to a carrier frequency for transmission over a wireless medium, one or more receive chains configured to down-convert signals received over the wireless medium from the carrier frequency to the baseband frequency, a power rail configured to provide a supply voltage to at least the one or more transmit chains and the one or more receive chains, and a first antenna element configured to transmit the upconverted signals over the wireless medium or to receive signals transmitted over the wireless medium. In some instances, the first antenna element may be formed using a first signal line associated with the transmit chains, a first signal line associated with the receive chains, or the power rail. In other instances, the first antenna element may be formed using segments of other signal lines or power rail of the wireless device.

Abstract: A wireless device includes one or more transmit chains configured to upconvert signals from a baseband frequency to a carrier frequency for transmission over a wireless medium, one or more receive chains configured to down-convert signals received over the wireless medium from the carrier frequency to the baseband frequency, a power rail configured to provide a supply voltage to at least the one or more transmit chains and the one or more receive chains, and a first antenna element configured to transmit the upconverted signals over the wireless medium or to receive signals transmitted over the wireless medium. The first antenna element may be formed using a first signal line associated with the transmit chains, a first signal line associated with the receive chains, or the power rail.

Abstract: A Bluetooth Low Energy (BLE) device may collect one or more resolvable public identifiers from one or more wireless devices, each of the resolvable public identifiers indicating whether a user associated with a respective one of the wireless devices is a possible virus carrier. The BLE device may generate a timestamp for each of the collected resolvable public identifiers, each timestamp indicating a time at which a corresponding resolvable public identifier was received by the BLE device. The BLE device may share the collected resolvable public identifiers and their corresponding timestamps with a paired device. The BLE device may receive, from the paired device, an indication of whether one or more of the collected resolvable public identifiers is associated with a possible virus carrier. The BLE device may be included within or attached to one of a bracelet, neckless, a belt, watch, a smartwatch, or a key fob.

Abstract: This disclosure provides a method and apparatus for saving and restoring state information of a wireless device with varying amounts of available power, such as wireless devices that may harvest power from radio-frequency signals. The wireless device may save and restore varying amounts of state information based at least in part on the amount of power available. In some embodiments, some of the stored state information may be lost as the available power decreases.

Abstract: This disclosure provides a method and apparatus for a staged wake-up of a wireless device. The wireless device may include a wireless wake-up receiver and a communication transceiver. The wireless device may begin operations in a low-power mode. The wireless wake-up receiver may identify radio-frequency (RF) activity and transition operation of the wireless device from the low-power mode to an active power mode when RF activity is identified. In some implementations, RF activity is identified when an energy pattern of a received RF signal is matched to an energy pattern associated with a known communication protocol.

Abstract: This disclosure provides a method and apparatus for controlling a plurality of radio-frequency (RF) power harvesters configured to generate power from received RF signals. A controller may monitor output power from the RF power harvesters and a sequence of reset signals. Based on the output powers and the sequence of reset signals, the controller may couple the RF power harvesters to a charge-storage device and one or more voltage regulators. In some implementations, the controller may also monitor RF envelope amplitude and couple the RF power harvesters to the charge storage device based on RF envelope amplitude.

Abstract: This disclosure provides a method and apparatus for optimizing power transfer from radio-frequency (RF) rectifiers to a voltage regulator. A first RF rectifier may be configured to generate a first voltage and a second RF rectifier may be configured to generate a second voltage, where the second voltage is an open circuit output voltage. The voltage regulator may regulate the first voltage to provide power. A controller may be configured to optimize power transfer from the first RF receiver to the voltage regulator based on the first voltage and the second voltage.

Abstract: This disclosure provides an active envelope detector to generate an output voltage based on an input radio-frequency (RF) signal. The active envelope detector includes a plurality of transistors configured to operate in a sub-threshold mode and generate an output voltage based on the input RF signal. A delta-modulation analog-to-digital converter (ADC) and a sigma-delta modulation ADC are provided. Both ADCs include an implementation of the active envelope detector to receive input RF signals.