Wireless charger with selective filtering of interference
An integrated circuit is described. This integrated circuit may include wireless-charger transmitter. The wireless-charger transmitter includes a driver circuit. Moreover, the wireless-charger transmitter selectively filters out an interference signal in a band of frequencies corresponding to AM radio. Note that the selective filtering may be performed by at least a filtering circuit. For example, the filtering circuit may include a low-pass filter. Moreover, the selective filtering using the filtering circuit may be based at least in part on a switching frequency of the wireless-charger transmitter. Furthermore, a filtering frequency associated with the filtering circuit (such as a 3 dB cutoff frequency of a low-pass filter) may be adjusted by selectively electrically coupling a set of capacitors in parallel with the filtering circuit.
1 . An integrated circuit, comprising a wireless-charger transmitter, wherein the wireless-charger transmitter comprises a driver circuit electrically coupled to a transmission coil; and
wherein the wireless-charger transmitter is configured to selectively filter out an interference signal in a band of frequencies corresponding to amplitude modulated (AM) radio;
wherein the selective filtering is performed by at least a filtering circuit;
wherein the selective filtering is based at least in part on a switching frequency of the wireless-charger transmitter; and
wherein, when the switching frequency has a first value, the filtering circuit is electrically coupled to the wireless-charger transmitter.
2 . The integrated circuit of claim 1 , wherein the filtering circuit comprises a low-pass filter.
3 . The integrated circuit of claim 1 , wherein the first value comprises 128 kHz.
4 . The integrated circuit of claim 1 , wherein, when the switching frequency has a second value, the filtering circuit is electrically decoupled from the wireless-charger transmitter.
5 . The integrated circuit of claim 4 , wherein the second value comprises 360 kHz.
6 . The integrated circuit of claim 1 , wherein the filtering circuit is selectively electrically coupled to or decoupled from the wireless-charger transmitter using one or more switches.
7 . The integrated circuit of claim 1 , wherein the integrated circuit is configured to adjust a filtering frequency associated with the filtering circuit by selectively electrically coupling a set of capacitors in parallel with the filtering circuit.
8 . The integrated circuit of claim 7 , wherein the set of capacitors comprises a parallel arrangement of one or more capacitors.
9 . The integrated circuit of claim 7 , wherein the filtering frequency comprises a 3 dB cutoff frequency of a low-pass filter.
10 . The integrated circuit of claim 1 , wherein the wireless-charger transmitter comprises a half-bridge circuit that is electrically coupled to the driver circuit.
11 . An electronic device, comprising:
an integrated circuit, wherein the integrated circuit comprises a wireless-charger transmitter;
wherein the wireless-charger transmitter comprises a driver circuit electrically coupled to a transmission coil; and
wherein the wireless-charger transmitter is configured to selectively filter out an interference signal in a band of frequencies corresponding to amplitude modulated (AM) radio;
wherein the selective filtering is performed by at least a filtering circuit;
wherein the selective filtering is based at least in part on a switching frequency of the wireless-charger transmitter;
wherein, when the switching frequency has a first value, the filtering circuit is electrically coupled to the wireless-charger transmitter; and
wherein, when the switching frequency has a second value that is larger than the first value, the filtering circuit is electrically decoupled from the wireless-charger transmitter.
12 . The electronic device of claim 11 , wherein the integrated circuit is configured to adjust a filtering frequency associated with the filtering circuit by selectively electrically coupling a set of capacitors in parallel with the filtering circuit.
13 . The electronic device of claim 12 , wherein the set of capacitors comprises a parallel arrangement of one or more capacitors.
14 . A method for performing wireless charging, comprising:
by a wireless-charger transmitter:
outputting, from a driver circuit, a charging signal to at least a transmission coil; and
selectively electrically coupling a filter circuit to the wireless-charger transmitter based at least in part on a switching frequency of the wireless-charger transmitter, wherein, when the switching frequency has a first value, the method comprises electrically coupling the filtering circuit to the wireless-charger transmitter; and
wherein, when the switching frequency has a second value that is larger than the first value, the method comprises electrically decoupling the filtering circuit from the wireless-charger transmitter.
15 . The electronic device of claim 11 , wherein the first value comprises 128 kHz.
16 . The electronic device of claim 11 , wherein the second value comprises 360 kHz.
17 . The method of claim 14 , wherein the first value comprises 128 kHz.
18 . The method of claim 14 , wherein the second value comprises 360 kHz.
19 . The method of claim 14 , wherein the method comprises adjusting a filtering frequency associated with the filtering circuit by selectively electrically coupling a set of capacitors in parallel with the filtering circuit.
20 . The method of claim 19 , wherein the filtering frequency comprises a 3 dB cutoff frequency of a low-pass filter.