The challenges in non invasive monitoring systems design for biopotentials acquisition, such as: low power consumption, low supply voltages, low cost and portability, have encourage electrical engineers to enhance the performance of such systems, beyond common specifications in order to develop medical care applications. This work propose a pre-amplifier based on the combination of a folded cascode topology, an offset compensation technique based on dc-feedback and a CMRR enhancement technique based on feed-forward combined with Quasi Floating Gates transistors and hardware reuse. Additionally, two filter stages, tunable band pass and tunable notch configurations to achieve tunability in cutoff frequencies according with the required medical application (EEG,ECG and EMG). In order to implement this system as an active electrode, the layout area minimization, low power consumption and low cost have been pursued in a CMOS technology of 0.05µm.