Abstract: A circuit for measuring signal output of a transducer includes an amplifier having a differential input and a single ended output referenced to a fixed potential. One transducer terminal is coupled through a source follower to an input terminal of the differential input and the other transducer terminal is coupled through a source follower and a resistive element to the other input terminal of the differential input whereby the transducer terminals are isolated from the fixed potential. A voltage to current converter converts the voltage at the single ended output to an output current that is applied to an input branch of a current mirror. A first output branch of the current mirror supplies a current equal to the converter output current to one terminal of the differential input. A second output branch of the current mirror supplies a current equal to the converter output current to the other terminal of the differential input.

Abstract: A CMOS differential amplifier is provided comprising a current supply coupled to a first terminal of a power supply. A first CMOS transistor is provided having a first source, a first gate, and a first drain coupled to the current supply. A second CMOS transistor is also provided having a second source, a second gate, and a second drain coupled to the current supply. The first and second gates are inputs to the CMOS differential amplifier. A resistance is coupled between a second terminal of the power supply and the first source of the first transistor and the second source of the second transistor to improve common-mode and ground noise suppression.