US 11,658,518 B2
Foreign objection detection sensing circuit for wireless power transmission systems
Baranidharan Karuppusamy, Singapore (SG); Thet Mon Sann, Singapore (SG); Kien Beng Tan, Singapore (SG); Supriya Raveendra Hegde, Edinburgh (GB); Huiqiao He, Singapore (SG); and Teerasak Lee, Singapore (SG)
Assigned to STMicroelectronics Asia Pacific Pte Ltd, Singapore (SG)
Filed by STMicroelectronics Asia Pacific Pte Ltd, Singapore (SG)
Filed on Aug. 23, 2021, as Appl. No. 17/408,824.
Application 17/408,824 is a division of application No. 17/037,982, filed on Sep. 30, 2020, granted, now 11,152,822.
Prior Publication US 2022/0103019 A1, Mar. 31, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. H02J 50/60 (2016.01); H02J 50/12 (2016.01)
CPC H02J 50/60 (2016.02) [H02J 50/12 (2016.02)] 16 Claims
OG exemplary drawing
 
1. A wireless power circuit operable in a transceiver mode and in a Q-factor measurement mode, comprising:
a coil having first and second terminals;
a bridge rectifier having a first input and a second input coupled to the first terminal and second terminal of the coil, respectively, and having an output coupled to a rectified voltage node;
an excitation circuit coupled to the first terminal of the coil and configured to drive the coil with a pulsed signal in the Q-factor measurement mode;
a protection circuit coupling the first terminal of the coil to a first node in the Q-factor measurement mode and decoupling the first terminal of the coil from the first node in the transceiver mode;
a controller configured to cause the bridge rectifier to short the first and second terminals of the coil to ground during Q-factor measurement mode; and
a Q-factor sensing circuit configured to:
amplify voltage at the first node to produce an output signal having an output voltage; and
in response to the voltage at the first node rising to cross a rising threshold voltage, take a sample of the output voltage to produce a digitized output voltage, and provide the digitized output voltage useful in calculating a Q-factor of the coil.