Wireless power receiver synchronization detection circuit
A wireless power receiver circuit includes an active rectifier circuit with a plurality of power transistors, wherein the active rectifier circuit is configured to rectify an induced AC receiver current. The wireless power receiver circuit includes also includes a gate drive controller circuit configured to sense the induced AC receiver current and to provide gate drive signals for the plurality of power transistors synchronized with the induced AC receiver current. The gate drive controller circuit includes a current sense circuit configured to provide two voltage signals having a difference proportional to the induced AC receiver current.
1. A wireless power receiver circuit, comprising:
an active rectifier circuit including a plurality of power transistors, wherein the active rectifier circuit is configured to rectify an induced AC receiver current;
a gate drive controller circuit configured to sense the induced AC receiver current and to provide gate drive signals to the plurality of power transistors synchronized with the induced AC receiver current,
wherein the gate drive controller circuit comprises a current sense circuit configured to provide two voltage signals having a difference proportional to the induced AC receiver current.
2. The wireless power receiver circuit of claim 1 , wherein the plurality of power transistors are GaN transistors.
3. The wireless power receiver circuit of claim 1 , further comprising a first winding of a transformer coupled to an input node of the active rectifier circuit, and wherein the current sense circuit comprises a second winding of the transformer, wherein the second winding has more coils than the first winding.
4. The wireless power receiver circuit of claim 3 , wherein the gate drive controller circuit comprises a magnitude detection circuit configured to receive the two voltage signals from the current sense circuit and output an enable signal if the induced AC receiver current is greater than a predetermined threshold.
5. The wireless power receiver circuit of claim 4 , wherein the gate drive controller circuit comprises a zero-crossing detection circuit configured to receive the two voltage signals from the current sense circuit and generate an output for driving the power transistors when the induced AC receiver current changes direction.
6. The wireless power receiver circuit of claim 5 , wherein the output of the zero-crossing detection circuit is enabled by a signal from the magnitude detection circuit if the induced AC receiver current is greater than the predetermined threshold.
7. The wireless power receiver circuit of claim 5 , further comprising a phase shifter circuit coupled to an output of the zero-crossing detection circuit to calibrate out system delay.
8. The wireless power receiver circuit of claim 7 , further comprising a gate driver integrated circuit coupled between an output of the phase shifter circuit and gate terminals of the power transistors.
9. The wireless power receiver circuit of claim 1 , wherein the gate drive controller circuit further comprises a voltage regulator circuit coupled to an output of the active rectifier circuit, and wherein the voltage regulator circuit is configured to power at least some components of the gate drive controller circuit.
10. The wireless power receiver circuit of claim 1 , wherein the active rectifier circuit and the the gate drive controller circuit are part of an integrated circuit.
11. The wireless power receiver circuit of claim 10 , further comprising a tuning circuit and a receiver coil coupled to the integrated circuit.