Design and Implementation of Amplifiers and High Pass Filters to Attenuate Low-Frequency Biomedical Signals

Abstract

Biomedical signals generally have a very small amplitude and are resistant to low-frequency interference so that they require signal conditioning before further analysis. This study aims to design and implement a series of amplifiers and high pass filters based on the LM 358 operational amplifier as a simulation medium for biomedical signal processing. The research method used is Research and Development (R&D) which includes literature study, system design, testing, and data analysis. The circuit consists of a high pass filter with a theoretical cut-off frequency of 106Hz and a non-inverting amplifier with a theoretical gain of 2 times. The test was carried out using a sinusoidal synth from the function generator with a frequency of 10 Hz to 2 kHz and a fixed input amplitude of 1 V. The test results showed that the circuit was able to dampen the signal at low frequencies and miss the signal at frequencies above the cut-off frequency. The output voltage is transient from 0.24 V at a frequency of 10 Hz to 2.4 V at a frequency of 2 kHz with a maximum gain of 7.15 dB. The comparison between the theoretical results and the test results showed the suitability of the circuit characteristics despite the differences caused by component tolerances, non-ideal IC characteristics, and measurement uncertainty. Overall, the designed circuit successfully performs the function of filtering and signal reinforcement so that it can be used as a learning medium for signal conditioning in medical electronics.