An apparatus comprising: a voltage-control loop including a first transistor and a first operational amplifier having its output connected to the gate terminal of the first transistor and operable to provide an output voltage (Vo) relative to a reference voltage, at the output of the first transistor; a current-control loop to sense current through the first transistor, relative to a reference current, having a second transistor (MN 2) and a second operational amplifier having its output connected to the gate terminal of the second transistor, to cause a constant current, through the first transistor, relative to a reference current, the second transistor being coupled in series with the first transistor, the second transistor to provide the constant current through the first and second transistors; characterized in that the apparatus comprises: a first capacitor including: a first node coupled to an output of the second operational amplifier of the current-control loop and the gate terminal of the second transistor and a second node (Vo) coupled to the output terminal of the first transistor and the input terminal of the second transistor; a second capacitor (Cb) with a first node coupled to an output of the first operational amplifier of the voltage-control loop and to the gate terminal of the first transistor, and a second node coupled to a supply node (Vcc) wherein the first capacitor and the second capacitor (Cb) are shorted at medium and high frequencies; a reference current generator (Iref) a first resistor including a first node coupled to a first input of the second operational amplifier and the input terminal of the first transistor, and a second node coupled to the supply node; and a second resistor including a first node coupled to a second input of the second operational amplifier and the reference current generator that provides the reference current, and a second node coupled to the supply node. a voltage-control loop including a first transistor and a first operational amplifier having its output connected to the gate terminal of the first transistor and operable to provide an output voltage (Vo) relative to a reference voltage, at the output of the first transistor; a current-control loop to sense current through the first transistor, relative to a reference current, having a second transistor (MN 2) and a second operational amplifier having its output connected to the gate terminal of the second transistor, to cause a constant current, through the first transistor, relative to a reference current, the second transistor being coupled in series with the first transistor, the second transistor to provide the constant current through the first and second transistors; characterized in that the apparatus comprises: a first capacitor including: a first node coupled to an output of the second operational amplifier of the current-control loop and the gate terminal of the second transistor and a second node (Vo) coupled to the output terminal of the first transistor and the input terminal of the second transistor; a second capacitor (Cb) with a first node coupled to an output of the first operational amplifier of the voltage-control loop and to the gate terminal of the first transistor, and a second node coupled to a supply node (Vcc) wherein the first capacitor and the second capacitor (Cb) are shorted at medium and high frequencies; a reference current generator (Iref) a first resistor including a first node coupled to a first input of the second operational amplifier and the input terminal of the first transistor, and a second node coupled to the supply node; and a second resistor including a first node coupled to a second input of the second operational amplifier and the reference current generator that provides the reference current, and a second node coupled to the supply node. a first capacitor including: a first node coupled to an output of the second operational amplifier of the current-control loop and the gate terminal of the second transistor and a second node (Vo) coupled to the output terminal of the first transistor and the input terminal of the second transistor; a second capacitor (Cb) with a first node coupled to an output of the first operational amplifier of the voltage-control loop and to the gate terminal of the first transistor, and a second node coupled to a supply node (Vcc) wherein the first capacitor and the second capacitor (Cb) are shorted at medium and high frequencies; a reference current generator (Iref) a first resistor including a first node coupled to a first input of the second operational amplifier and the input terminal of the first transistor, and a second node coupled to the supply node; and a second resistor including a first node coupled to a second input of the second operational amplifier and the reference current generator that provides the reference current, and a second node coupled to the supply node.