A method of starting a circuit, the method comprising: receiving a first voltage at a drain node (VD) of a start-up circuit comprising a first gallium nitride, GaN, transistor (M 1 ) having a drain coupled to the drain node (VD), a second GaN transistor (M 2 A) having a drain coupled to the drain node (VD) and a gate coupled to a reference node (GND), and a first capacitor (CA) coupled between the gate and a source of the second GaN transistor (M 2 A); charging the first capacitor (CA) via the second GaN transistor (M 2 A); providing energy from the first capacitor (CA) to a driver circuit coupled to a gate of the first GaN transistor (M1); and turning-off the second GaN transistor (M2A) when a voltage of the first capacitor (CA) reaches a threshold; wherein the start-up circuit further comprises: a third GaN transistor (M 2 B) having a drain coupled to the gate of the second GaN transistor (M 2 A), and a gate coupled to the reference node (GND), wherein the gate of the second GaN transistor (M 2 A) is coupled to the reference node (GND) via a load path of the third GaN transistor (M2B); and a second capacitor (CB) coupled between a source of the third GaN transistor (M 2 B) and the reference node (GND); and wherein the first GaN transistor (M 1 ) is a normally-off transistor and the second and third GaN transistors (M 2 A, M 2 B) are normally-on transistors. receiving a first voltage at a drain node (VD) of a start-up circuit comprising a first gallium nitride, GaN, transistor (M 1 ) having a drain coupled to the drain node (VD), a second GaN transistor (M 2 A) having a drain coupled to the drain node (VD) and a gate coupled to a reference node (GND), and a first capacitor (CA) coupled between the gate and a source of the second GaN transistor (M 2 A); charging the first capacitor (CA) via the second GaN transistor (M 2 A); providing energy from the first capacitor (CA) to a driver circuit coupled to a gate of the first GaN transistor (M1); and turning-off the second GaN transistor (M2A) when a voltage of the first capacitor (CA) reaches a threshold; wherein the start-up circuit further comprises: a third GaN transistor (M 2 B) having a drain coupled to the gate of the second GaN transistor (M 2 A), and a gate coupled to the reference node (GND), wherein the gate of the second GaN transistor (M 2 A) is coupled to the reference node (GND) via a load path of the third GaN transistor (M2B); and a second capacitor (CB) coupled between a source of the third GaN transistor (M 2 B) and the reference node (GND); and wherein the first GaN transistor (M 1 ) is a normally-off transistor and the second and third GaN transistors (M 2 A, M 2 B) are normally-on transistors. a third GaN transistor (M 2 B) having a drain coupled to the gate of the second GaN transistor (M 2 A), and a gate coupled to the reference node (GND), wherein the gate of the second GaN transistor (M 2 A) is coupled to the reference node (GND) via a load path of the third GaN transistor (M2B); and a second capacitor (CB) coupled between a source of the third GaN transistor (M 2 B) and the reference node (GND); and wherein the first GaN transistor (M 1 ) is a normally-off transistor and the second and third GaN transistors (M 2 A, M 2 B) are normally-on transistors. <EOS>