Abstract: An operational amplifier circuit is described. The operational amplifier circuit includes an operational amplifier, a high-pass filter portion, and a feedback loop, wherein the operational amplifier circuit is configured to output an amplified filtered version of a bio-signal. The operational amplifier includes a non-inverting input terminal, and an inverting input terminal, wherein the inverting input terminal and the non-inverting input terminal are configured to be coupled to a common reference potential through resistors. The high-pass filter portion is configured to receive a bio-signal as input and to provide input to the non-inverting input terminal of the operational amplifier. The feedback loop includes a low-pass filter portion, wherein the low-pass filter portion is configured to receive input from an output of the operational amplifier and to provide input to the inverting input terminal of the operational amplifier.