Systems and methods for sense FET calibration

A method for circuit calibration, the method comprising:

• providing a reference current;
• providing a sense circuit, wherein the sense circuit is electrically coupled to the reference current, and wherein the sense circuit provides a sense current;
• and
• providing a calibration circuit, wherein the calibration circuit includes:
• a calibration amplifier electrically coupled to the reference current and to the sense current, wherein the calibration amplifier outputs a calibration signal representing a difference between the reference current and the sense current;
• and
• a sample and hold circuit, wherein the sample and hold circuit is operable to store a value representative of the calibration signal;
• and
• controlling a calibration control signal, wherein the value stored in the sample and hold circuit is updated and used for calibration wherein controlling the calibration control signal includes:
• activating the calibration control signal, wherein the value stored in the sample and hold circuit is updated;
• and
• deactivating the calibration control signal, wherein a current derived from the value stored in the sample and hold circuit is aggregated with the sense current to form a calibrated current, and wherein the calibrated current is the sense current with a sense circuit offset error and a sense circuit temperature coefficient error substantially removed.

A circuit for calibration, the circuit comprising:

• a reference current;
• a sense circuit, wherein the sense circuit is electrically coupled to the reference current, wherein the sense circuit includes a sense operational amplifier that provides a sense current;
• a calibration circuit, wherein the calibration circuit includes:
• a calibration operational amplifier coupled to a derivative of the reference current and to the sense current, wherein the calibration operational amplifier outputs a calibration signal representing a difference between the derivative of the reference current and the sense current;
• and
• a sample and hold circuit, wherein the sample and hold circuit is operable to store a value representative of the calibration signal wherein the circuit further comprises:
• a sense FET electrically coupled to a feedback loop of the sense operational amplifier, and having a first aspect;
• and
• a calibration FET electrically coupled to the reference current, and having a second aspect;
• and wherein a ratio of the derivative of the reference current to the sense current is the same as a ratio between the second aspect and the first aspect.