A driver (202, 900) for generating gate drive signals for a plurality of switches of an inductor-inductor-capacitor; LLC; resonant converter, the LLC resonant converter comprising: a switching network comprising a first switch and a second switch connected in series and a third switch and a fourth switch connected in series; and a resonant tank connected between the switching network and a primary side of a transformer; and a rectifier coupled to a secondary side (NS1, NS2) of the transformer; and the driver (202, 900) configured to be coupled to the switching network and the rectifier, said driver comprising: a bridge coupled between a bias voltage and ground, a resonant device coupled to the bridge, and a signal transformer coupled to the resonant device; wherein the bridge is configured to couple to the LLC resonant converter and comprises: a first switch and a second switch connected in series and coupled between the bias voltage and ground and providing a first common node (node B), wherein the first common node (node B) is configured to couple to a first low side gate drive signal of the plurality of switches of the LLC resonant converter; and a third switch and a fourth switch connected in series and coupled between the bias voltage and ground and providing a second common node (node A), wherein the second common node (node A) is configured to couple to a second low side gate drive signal of the plurality of switches of the LLC resonant converter; wherein the resonant device comprises a fixed capacitance (C6, C8) which is connected to the bridge and forms a resonant process together with a gate capacitance of the LLC resonant converter and a magnetizing inductance (Lm) of the signal transformer, characterised in that the resonant device comprises an adjustable capacitance, the adjustable capacitance is implemented as a plurality of capacitors (Cn), each capacitor is connected in series with an auxiliary switch (Sn) to form a switchable capacitor; wherein the signal transformer comprises: a primary winding (Dpri); and a plurality of secondary windings configured to couple to gate drive signals of the LLC resonant converter, wherein a first winding of the secondary windings (Dsec_1) configured to couple to a secondary side gate drive signal of the LLC resonant converter; a second winding of the secondary windings (Dsec_2) configured to couple to a first high side gate drive signal of the LLC resonant converter; and a third winding of the secondary windings (Dsec_3) configured to couple to a second high side gate drive signal of the LLC resonant converter; the driver further comprises a Maximum Efficiency Point Tracking; MEPT; detector and a control circuit; the MEPT detector is configured to detect the voltage across node A and node B, and send the detected signal to the control circuit; wherein the node B is the first common node, and the node A is the second common node; the control circuit is configured to find a lowest point of the detected signal; and the control circuit is further configured to adjust the resonant frequency of the driver through turning on/off the switchable capacitors until the resonant frequency of driver matches the switch frequency of the resonant converter, if the detected signal is greater than the lowest point. a switching network comprising a first switch and a second switch connected in series and a third switch and a fourth switch connected in series; and a resonant tank connected between the switching network and a primary side of a transformer; and a rectifier coupled to a secondary side (NS1, NS2) of the transformer; a first switch and a second switch connected in series and coupled between the bias voltage and ground and providing a first common node (node B), wherein the first common node (node B) is configured to couple to a first low side gate drive signal of the plurality of switches of the LLC resonant converter; and a third switch and a fourth switch connected in series and coupled between the bias voltage and ground and providing a second common node (node A), wherein the second common node (node A) is configured to couple to a second low side gate drive signal of the plurality of switches of the LLC resonant converter; a primary winding (Dpri); and a plurality of secondary windings configured to couple to gate drive signals of the LLC resonant converter, wherein a first winding of the secondary windings (Dsec_1) configured to couple to a secondary side gate drive signal of the LLC resonant converter;