An integrated, fully-differential current-feedback transimpedance operational amplifier circuit is disclosed. The circuit can be configured as a class-AB, low-impedance input stage, followed by an inverter-based, rail-to-rail output stage. For enhancing the open-loop transimpedance gain of the amplifier without consuming additional DC power, the same bias current is used both in the input stage and in a gain-enhancement stage serving as its load. The gain-enhancement stage can be either DC- or AC-coupled to the input of the amplifier. In the case of DC coupling, an output common-mode feedback loop can be used to provide the proper operating voltages in the amplifier.
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