Design of Low Pass Filter to Reduce Noise on ECG Signal Based on IC LM358

The Electrocardiogram (ECG) signal is an important biomedical signal that is used to record the electrical activity of the heart. In the ECG signal acquisition process, high-frequency noise contamination often occurs that can disrupt clinical analysis. This research designs and tests an active Low Pass Filter (LPF) circuit based on the IC LM358 with a 100 nF capacitor to reduce noise in the ECG signal. Testing was performed by varying the resistor values to 100 Ω, 680 Ω, 1 kΩ, 10 kΩ, 100 kΩ, and 1 MΩ to obtain different cut-off frequencies for each configuration. The test results show that the larger the resistor value, the lower the cut-off frequency and attenuation at high frequencies, is better. The 1 MΩ resistor yields a cut-off frequency of about 1.59 Hz with the steepest output voltage drop from 0.25 V at 5 Hz to 0.055 V at 100 Hz. The 10 kΩ resistor configuration is considered the most optimal for ECG applications because it yields a cut-off frequency of ≈ 159 Hz that still covers the entire bandwidth diagnostic ECG signal (0.5–150 Hz) with characteristics of high-frequency attenuation that is good.