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.

Abstract: Method and apparatus for wirelessly transmitting and receiving power between devices are provided. A first device may convert power into RF energy and transmit the RF energy to a second device. In some implementations, the first device may steer the RF energy using beamforming techniques to the second device. The second device may receive and convert the RF energy into power for the second device. In some implementations, the second device may be powered solely or in part by power transmitted by the first device. In some implementations, the first device may include two or more RF energy harvesters and a power combiner. The power combiner may combine power from the two or more RF energy harvesters to power the second device and/or charge a battery.

Abstract: Method and apparatus for controlling the power consumption of a wireless device are provided. A wireless device may include a configurable radio frequency (RF) front-end that may be configured to use fewer hardware stages and/or processing steps to reduce power consumption based at least in part on a signal quality, detected interference, or system information associated with a received RF signal. In some implementations, the configurable RF front-end may be configured to consume less power while receiving strong RF signals and configured to consume more power while receiving weak RF signals.

Abstract: Method and apparatus for generating and receiving a paging signal are provided. The paging signal may be received by a wireless device in a low-power state. The paging signal may include a target identification (ID) that may be associated with the wireless device. If the target ID is associated with the wireless device, the wireless device may leave the low-power state, enter an active power state and communicate with other wireless devices. The wireless device may include power harvesting circuitry to convert RF energy from the paging signal into power to operate a portion of the wireless device.