Apparatus and methods for real-time resonance adaptation for power receiver
View Patent ↗Wirelessly powered receiver system and sensors are described. In an embodiment, the power receiver system, includes an inductive coil that receives wireless power from an external transmitter, a capacitor bank that optimizes power transfer to an energy harvesting device, and a power-receiving frontend RF-DC rectifier with a periodically enabled closed feedback loop that adapts settings of the capacitor bank in real-time to adapt to changes on the inductive coil to maximize power transfer efficiency.
1 . A power receiver system, comprising:
an inductive coil that receives wireless power from an external transmitter;
a capacitor bank that optimizes power transfer to an energy harvesting device; and
a power-receiving frontend RF-DC rectifier with a periodically enabled closed feedback loop that adapts settings of the capacitor bank in real-time to adapt to changes on the inductive coil to maximize power transfer efficiency.
2 . The power receiver system of claim 1 , wherein the capacitor bank comprises a binary-weighted capacitor bank implemented in parallel with a Dickson-stage passive rectifier.
3 . The power receiver system of claim 1 , wherein the closed feedback loop mitigates resonance variations due to at least one of different dielectric environments, loading conditions, and fabrication mismatches.
4 . The power receiver system of claim 1 , wherein the capacitor bank is a 6-bit capacitor bank that is periodically adjusted using a successive-approximation-resonance-tuning process.
5 . The power receiver system of claim 1 , wherein the closed feedback loop comprises detecting swings corresponding to two consecutive capacitor bank selections and sampling on two hold capacitors respectively.
6 . The power receiver system of claim 5 , wherein an impedance of the inductive coil is approximately symmetric against the offset of the resonance capacitor.
7 . The power receiver system of claim 1 , further comprising a transmitter that transmits information to an external controller.
8 . The power receiver system of claim 7 , wherein the transmitter is an ultra-wideband impulse radio (IR-UWB) transmitter as a back telemetry for output voltage regulation, wherein an output voltage from the IR-UWB transmitter is regulated based on back telemetry transmitting the real-time harvested voltage reading.
9 . The power receiver system of claim 1 , wherein operations are heavily duty-cycled to reduce power consumption.
10 . The power receiver system of claim 1 , further comprising:
a coarse bandgap reference (BGR-course) and a local low-dropout regulator (LDO) that generates a voltage supply for the internal circuitry; and a fine bandgap reference (BGR-fine) that generates a stable voltage reference.
11 . A wirelessly powered sensor chip, comprising:
an inductive coil that receives wireless power from an external transmitter;
a capacitor bank that specifies different settings for different external environments surrounding the sensor chip;
a power-receiving frontend RF-DC rectifier with a periodically enabled closed feedback loop that adapts settings of the capacitor bank in real-time to adapt to the surrounding environment; and
a transmitter that transmits information related to the capacitor settings and voltage readings to an external controller.
12 . The wirelessly powered sensor chip of claim 11 , wherein the capacitor settings are used to determine a type of material in the surrounding environment.
13 . The wirelessly powered sensor chip of claim 11 , wherein changes to an impedance of the inductive coil result in changes to the capacitor settings and are used to detect near-field changes in the surrounding environment.
14 . The wirelessly powered sensor chip of claim 11 , wherein changes to a voltage reading without changes to the capacitor settings are used to detect far-field changes in the surrounding environment.
15 . The wirelessly powered sensor chip of claim 11 , wherein the capacitor bank comprises a binary-weighted capacitor bank implemented in parallel with a Dickson-stage passive rectifier.
16 . The wirelessly powered sensor chip of claim 11 , wherein the closed feedback loop mitigates resonance variations due to at least one of different dielectric environments, loading conditions, and fabrication mismatches.
17 . The wirelessly powered sensor chip of claim 11 , wherein the capacitor bank is a 6-bit capacitor bank that is periodically adjusted using a successive-approximation-resonance-tuning process.
18 . The wirelessly powered sensor chip of claim 11 , wherein the closed feedback loop comprises detecting swings corresponding to two consecutive capacitor bank selections and sampling on two hold capacitors respectively.
19 . The wirelessly powered sensor chip of claim 11 , wherein an impedance of the inductive coil is approximately symmetric against the offset of the resonance capacitor.
20 . The wirelessly powered sensor chip of claim 11 , wherein the transmitter is an ultra-wideband impulse radio (IR-UWB) transmitter as a back telemetry for output voltage regulation, wherein an output voltage from the IR-UWB transmitter is regulated based on back telemetry transmitting the real-time harvested voltage reading.
21 . A sensor system comprising:
an implantable sensor chip configured for placement relative to a surrounding environment, comprising:
an inductive coil configured to receives power from an external transmitter;
a capacitor bank having an input coupled to the inductive coil, the capacitor bank comprising a plurality of capacitors configured to be selectively included in one or more of a plurality of capacitor-bank settings;
an amplitude detector having an input coupled to the input of the capacitor bank and an output, the amplitude detector configured to provide measurements of the input of the capacitor bank;
a resonance compensator having outputs coupled to the capacitor bank and an input coupled to the output of the amplitude detector, the resonance compensator configured to: sample the measurements of the input of the capacitor bank through the amplitude detector, and select an optimal capacitor-bank setting based on the measurements of the input of the capacitor bank in real-time to adapt to the surrounding environment;
a transmitter configured to transmit information related to the capacitor-bank settings and voltage readings; and
an external controller configured to receive and process the transmitted information related to the capacitor-bank settings and voltage readings to determine as aspect of the surrounding environment.
22 . The sensor system of claim 21 , wherein the external controller is configured to determine a type of material in the surrounding environment based on the capacitor-bank settings.
23 . The sensor system of claim 21 , wherein the external controller is configured to detect near-field changes in the surrounding environment based on changes to the capacitor-bank settings.
24 . The sensor system of claim 21 , wherein the external controller is configured to detect far-field changes in the surrounding environment based on changes to a voltage reading without changes to the capacitor-bank settings.