A method, apparatus and system of constant output common mode voltage of a pre-amplifier circuit are disclosed. In one embodiment, a system includes a first circuit, a comparator circuit coupled with an output of the first circuit, a pre-amplifier circuit of the comparator circuit, a tracking circuit coupled with a common output location of the pre-amplifier circuit to provide (e.g., source/sink) an additional current to the common output location of the pre-amplifier circuit using an alternate current path in the tracking circuit when an input common mode of the pre-amplifier circuit is beyond a saturation range, and a second circuit of the comparator circuit coupled with the pre-amplifier circuit. A scaled version of a pair of input transistors of a pre-amplifier circuit of the tracking circuit may be created using a scaling factor (‘N’).