Multimode wireless power receiver circuit
A multimode receiver can include on or more of an over-voltage protection circuit or a high frequency mode switch. As such, some embodiments of a multi-mode receiver includes a rectifier; a high frequency circuit coupled to the rectifier; a low frequency circuit coupled to the rectifier; and a switching circuit coupled to disable at least a portion of the low frequency circuit while the multi-mode receiver operates in high frequency mode. In some embodiments, the multimode receiver further includes a high-voltage protection circuit coupled to the high frequency circuit that detunes the high frequency circuit when a high-voltage condition is detected.
1. A multi-mode receiver, comprising:
a rectifier;
a high frequency circuit with a high frequency coil, coupled to the rectifier;
a low frequency circuit with a low frequency coil, coupled to the rectifier, wherein the low frequency coil is separate from the high frequency coil; and
a switching circuit coupled to provide additional capacitance to the low frequency circuit, at least partially disabling the low frequency circuit, while the multi-mode receiver operates in high frequency mode.
2. The receiver of claim 1 , wherein the low frequency circuit includes:
a shunt capacitor coupled in parallel with the low frequency coil,
wherein the switching circuit is configured to couple both sides of the shunt capacitor to a ground through capacitors in high frequency mode.
3. The receiver of claim 2 , wherein the switching circuit comprises:
a first transistor configured to couple a first side of the shunt capacitor to the ground through a first capacitor; and
a second transistor configured to couple a second side of the shunt capacitor to the ground through a second capacitor,
wherein a controller provides a signal to gates of the first transistor and the second transistor, the signal depending on high frequency operation.
4. The receiver of claim 1 , further including an over voltage protection circuit coupled to the high frequency circuit.
5. The receiver of claim 4 , wherein the over voltage protection circuit de-tunes the high frequency circuit when an over voltage condition is detected.
6. The receiver of claim 5 , wherein the over-voltage protection circuit includes
an overvoltage protection circuit configured to provide an overvoltage signal when the overvoltage condition is detected; and
transistors driven by the overvoltage signal of the overvoltage protection circuit to change a resonant frequency of the high frequency circuit.
7. A method of receiving power wirelessly, comprising:
detecting a low frequency mode or a high frequency mode of power receipt;
receiving power in a low frequency circuit with a low frequency coil if the low frequency mode is detected;
at least partially disabling the low frequency circuit with the low frequency coil by applying additional capacitance across the low frequency coil and receiving power in a high frequency circuit if the high frequency mode is detected, wherein the low frequency coil is separate from the high frequency coil; and
rectifying power from the low frequency circuit and the high frequency circuit with a single rectifier.
8. The method of claim 7 , wherein disabling the low frequency circuit comprises:
coupling both sides of a shunt capacitor in the low frequency circuit to a ground through a capacitance when a high frequency mode is detected.
9. A receiver, comprising:
a high frequency receiver including a first inductor coupled in parallel with a first capacitor;
a low frequency receiver including a second inductor coupled in parallel with a second capacitor;
a rectifier coupled across the high frequency receiver;
a switching circuit coupled to disable a part of the low frequency receiver by applying additional capacitance during operation of the high frequency receiver; and
an over-voltage protection circuit coupled across the high frequency receiver, the over-voltage protection circuit de-tuning the high frequency receiver when an overvoltage condition is detected.