Circuit having sample and hold feedback control and method

A method for maintaining an operating state of a circuit, comprising:

• storing energy in a first energy storage element using a first portion of a pulse, wherein storing the energy in the first energy storage element comprises:
• using the first portion of the pulse to close first and second switches, wherein closing the first switch electrically couples the first node to the first energy storage element;
• and
• charging the first energy storage element using the first voltage at the first node;
• using the energy stored in the first energy storage element during a second portion of the pulse to generate an error signal;
• using the error signal to generate a drive signal;
• and
• generating a first voltage at a first node from the drive signal.

A driver circuit, comprising:

• an operational amplifier having first and second input terminals and an output terminal;
• a first switch having a control terminal and first and second terminals, the control terminal coupled for receiving a control signal and the first terminal coupled to the first terminal of the operational amplifier;
• a second switch having a control terminal and first and second terminals, the control terminal of the second switch coupled to the control terminal of the first switch and for receiving the control signal, and the first terminal of the second switch coupled to the second terminal of the first switch;
• a first current source having first and second current conducting terminals, the first current conducting terminal coupled to the second terminal of the second switch;
• and
• a first energy storage element having first and second terminals, the first terminal of the first energy storage element coupled to the first input terminal of the operational amplifier.