A circuit, comprising: a high side power transistor; a high side cascode transistor; wherein the high side power transistor and high side cascode transistor are connected in series between a power supply voltage (Vdd) and a switching node; a low side power transistor; a low side cascode transistor; wherein the low side power transistor and low side cascode transistor are connected in series between the switching node and a reference voltage (Gnd); a high side gate driver circuit having an output driving a control terminal of the high side power transistor, wherein the high side gate driver circuit has a first power supply node coupled to receive the power supply voltage (Vdd) and a second power supply node coupled to receive a floating ground voltage (Vfg) that is also applied to a control terminal of the high side cascode transistor; a low side gate driver circuit having an output driving a control terminal of the low side power transistor, wherein the low side gate driver circuit has a first power supply node coupled to receive a floating supply voltage (Vfs) that is also applied to a control terminal of the low side cascode transistor and a second power supply node coupled to receive the reference voltage (Gnd); a first variable voltage generator configured to generate the floating ground voltage (Vfg), wherein the floating ground voltage (Vfg) tracks the reference voltage (Gnd) over a lower range of voltage levels for said power supply voltage (Vdd) and further satisfies a first ratio metric relationship dependent on the difference between the power supply voltage (Vdd) and the reference voltage (Gnd) over a higher range of voltage levels for said power supply voltage (Vdd); and a second variable voltage generator configured to generate the floating supply voltage (Vfs), wherein the floating supply voltage (Vfs) tracks the power supply voltage (Vdd) over the lower range of voltage levels for said power supply voltage (Vdd) and further satisfies a second ratio metric relationship dependent on the difference between the power supply voltage (Vdd) and reference voltage (Gnd) over the higher range of voltage levels for said power supply voltage (Vdd); wherein the first and second ratio metric relationships are different. a high side power transistor; a high side cascode transistor; wherein the high side power transistor and high side cascode transistor are connected in series between a power supply voltage (Vdd) and a switching node; a low side power transistor; a low side cascode transistor; wherein the low side power transistor and low side cascode transistor are connected in series between the switching node and a reference voltage (Gnd); a high side gate driver circuit having an output driving a control terminal of the high side power transistor, wherein the high side gate driver circuit has a first power supply node coupled to receive the power supply voltage (Vdd) and a second power supply node coupled to receive a floating ground voltage (Vfg) that is also applied to a control terminal of the high side cascode transistor; a low side gate driver circuit having an output driving a control terminal of the low side power transistor, wherein the low side gate driver circuit has a first power supply node coupled to receive a floating supply voltage (Vfs) that is also applied to a control terminal of the low side cascode transistor and a second power supply node coupled to receive the reference voltage (Gnd); a first variable voltage generator configured to generate the floating ground voltage (Vfg), wherein the floating ground voltage (Vfg) tracks the reference voltage (Gnd) over a lower range of voltage levels for said power supply voltage (Vdd) and further satisfies a first ratio metric relationship dependent on the difference between the power supply voltage (Vdd) and the reference voltage (Gnd) over a higher range of voltage levels for said power supply voltage (Vdd); and a second variable voltage generator configured to generate the floating supply voltage (Vfs), wherein the floating supply voltage (Vfs) tracks the power supply voltage (Vdd) over the lower range of voltage levels for said power supply voltage (Vdd) and further satisfies a second ratio metric relationship dependent on the difference between the power supply voltage (Vdd) and reference voltage (Gnd) over the higher range of voltage levels for said power supply voltage (Vdd); wherein the first and second ratio metric relationships are different.