An apparatus comprising: a plurality of power-gate transistors controllable by a digital bus, the plurality of power-gate transistors integrating a low dropout regulator and operable to provide a first power supply to a load, and to receive a second power supply as input, wherein the first and second power supplies are DC-power supplies; an analog-to-digital converter, ADC, to receive the first power supply and to generate a digital output representative of a supply voltage the first power supply; and a controller to receive the digital output representative of the first power supply and to generate the digital bus signal for controlling the plurality of power-gate transistors such that a transfer function of the plurality of power-gate transistors is linear over an operating range, wherein the controller is operable to modify gain of a loop formed by the plurality of transistors, the ADC and the controller, and wherein the controller is further operable to modify the gain of the loop as a function of an operating point, wherein the controller comprises: a first plurality of delay units (301, 302) coupled together in series, wherein one of the delay units of the first plurality of delay units receives the digital output representative of the supply voltage of the first power supply; a first plurality of gain stages (303, 304, 305) to amplify gain of outputs of each of the first plurality of delay units; and a summer to sum the amplified outputs to generated summed output, and wherein the controller further comprises: a multiplier to multiply the summed output by a factor to modify the gain of the loop such that the transfer function of the plurality of power-gate transistors is linear over an operating range. a plurality of power-gate transistors controllable by a digital bus, the plurality of power-gate transistors integrating a low dropout regulator and operable to provide a first power supply to a load, and to receive a second power supply as input, wherein the first and second power supplies are DC-power supplies; an analog-to-digital converter, ADC, to receive the first power supply and to generate a digital output representative of a supply voltage the first power supply; and a controller to receive the digital output representative of the first power supply and to generate the digital bus signal for controlling the plurality of power-gate transistors such that a transfer function of the plurality of power-gate transistors is linear over an operating range, wherein the controller is operable to modify gain of a loop formed by the plurality of transistors, the ADC and the controller, and wherein the controller is further operable to modify the gain of the loop as a function of an operating point, wherein the controller comprises: a first plurality of delay units (301, 302) coupled together in series, wherein one of the delay units of the first plurality of delay units receives the digital output representative of the supply voltage of the first power supply; a first plurality of gain stages (303, 304, 305) to amplify gain of outputs of each of the first plurality of delay units; and a summer to sum the amplified outputs to generated summed output, and wherein the controller further comprises: a multiplier to multiply the summed output by a factor to modify the gain of the loop such that the transfer function of the plurality of power-gate transistors is linear over an operating range. a first plurality of delay units (301, 302) coupled together in series, wherein one of the delay units of the first plurality of delay units receives the digital output representative of the supply voltage of the first power supply; a first plurality of gain stages (303, 304, 305) to amplify gain of outputs of each of the first plurality of delay units; and a summer to sum the amplified outputs to generated summed output, and wherein the controller further comprises: a multiplier to multiply the summed output by a factor to modify the gain of the loop such that the transfer function of the plurality of power-gate transistors is linear over an operating range.