Patent ID: 7218154

Claim:
A track and hold offset compensated amplifier circuit configured to operate in a tracking phase and a holding phase, the track and hold circuit comprising: a trans-conductance operational amplifier, having a positive input terminal, a negative input terminal and an output terminal; an output stage circuit having an input terminal and an output terminal, wherein the output terminal of the output stage circuit is selectively electrically connected to the negative input terminal of the operational amplifier during the tracking phase; a sampling switch configured to electrically connect the output terminal of the operational amplifier with the input terminal of the output stage circuit during the tracking phase, and configured to electrically disconnect the output terminal of the operational amplifier from the input terminal of the output stage circuit during the holding phase; a capacitor electrically connected to the input terminal of the output stage circuit so as to charge or discharge during the tracking phase, and so as to hold charge relatively constant during the holding phase; and a comparison circuit configured to evaluate a sign or sign and value of the current at the output terminal of the trans-conductance operational amplifier when kept at the potential of the input terminal of the output stage circuit at least during a portion of the holding phase, wherein the comparison circuit is further configured to increase or decrease a voltage differential applied between the positive and negative input terminals of the trans-conductance operational amplifier depending on a result of the evaluation of the comparison circuit.