Current sensing circuit

Claim 1

A current sensing circuit for providing an output signal proportional to current passing through a conductor provided by a supply voltage, the current sensing circuit comprising: first and second bipolar transistors, each having a base terminating region, a collector terminating region, and an emitter terminating region; a sensing impedance in series with said conductor, and electrically connected between said base terminating region of said first bipolar transistor and said base terminating region of said second bipolar transistor; first and second field effect transistors, each having a gate terminating region, a source terminating region, and a drain terminating region, said source terminating region of said first field effect transistor electrically connected to said collector terminating region of said first bipolar transistor, and said source terminating region of said second field effect transistor electrically connected to said collector terminating region of said second bipolar transistor, said gate terminating regions of said first and second field effect transistors electrically connected in common; bias voltage means, coupled to said supply voltage, for providing a bias voltage at a bias output means thereof which varies substantially in proportion to said supply voltage, and where said bias output means is electrically connected to said common gate regions of said first and second field effect transistors; and a negative feedback amplifier means having a positive input means and a negative input means, and an output means, said negative feedback amplifier including a selected impedance electrically connected between said negative input means and said output means, said negative input means electrically connected to said drain terminating region of said first field effect transistor, and said positive input means electrically connected to said drain terminating region of said second field effect transistor.