An amplifier includes a first stage and a second stage. The first stage includes a first output and a second output. The second stage includes an output, a first transistor and a second transistor. The first transistor includes a drain coupled to the first output of the first stage, and a source coupled to the output of the second stage. The second transistor includes a drain coupled to the second output of the first stage, and a gate coupled to the output of the second stage.

An amplifier includes a first stage and a second stage. The first stage includes a first output, and a second output. The second stage includes a first transistor, a second transistor, and a common-mode circuit. The first transistor includes a drain coupled to the first output of the first stage. The second transistor includes a drain coupled to the second output of the first stage. The common-mode circuit includes a reversible current mirror circuit coupled to the drain of the first transistor and the drain of the second transistor.

An amplifier includes a first stage and a second stage. The first stage includes a first output and a second output. The second stage includes an output, a first transistor and a second transistor. The first transistor includes a drain coupled to the first output of the first stage, and a source coupled to the output of the second stage. The second transistor includes a drain coupled to the second output of the first stage, and a gate coupled to the output of the second stage.