In any biomedical signal acquisition system, a front-end amplifier is needed to amplify low amplitude bio-signals while filtering out any unwanted low-frequency artifacts. The design of low frequency poles within the sub-Hz range implies very large time-constants which goes against system integrability. In recent years, the pseudo resistor has been used to provide very large on-chip resistance to achieve sub-Hz pole frequency. However, the pseudo resistor behaves poorly across PVT variations and is highly non-linear which makes the low-frequency pole unpredictable.
In this thesis, a bio-LNA utilizing a differential difference amplifier structure along with gm-C filters is examined. The differential topology provides high CMRR while the negative feedback through the gm-C filter provides the low-frequency pole. A capacitor multiplier is also implemented to achieve a very high value effective on-chip capacitance. The functionality of the bio-LNA is validated through simulations in Cadence.