Patent ID: 7034542

Claim:
A current sensing circuit, comprising: a sense FET with an input at its gate; an operational amplifier circuit with an input responsively coupled to the sense FET; the operational amplifier operable to force the same drain voltage across the sense FET as across a main power FET a first FET with a first polarity within the operational amplifier; a second FET with an opposite polarity of the first FET, the second FET within the operational amplifier and being responsively coupled in series with the first FET; the sense FET operable to provide a current to the operational amplifier that is the difference between the drain current I 1 of first FET and the drain current I 2 of the second FET; at least three current mirrors; a first current mirror and a second current mirror operable to extract replica copies of the drain current I 1 from the first FET and the drain current I 2 of the second FET, respectively; and a third current mirror responsively coupled to the first current mirror and the second current mirror and operable to output a current that is a multiple of the sense FET current.