BSP2

Mono-lead ECG Amplifier

The objective is to design a sensitive amplifier circuit that can detect ECG (Electrocardiogram) signals obtained from metal electrodes applied at the left arm (LA), right arm (RA) and right leg(RL).

The circuit basically amplifies the difference between the right-arm (RA) lead and the left-arm (LA) lead with the right-leg (RL) lead as the ground or reference node. The circuit consists of a “difference” amplifier which is essentially a 2-stage instrumentation amplifier (IA) followed by a band-pass filter, a 2-stage power frequency notch filter and another amplifier stage.

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Schematic Diagram - PCB 1

1) Instrumentation preamplifier

2) Band-pass filter (0.22-109.8Hz)

3) First stage of the line-frequency notch filter

4) Main amplifier

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Schematic Diagram - PCB 2

1) Second stage of the line-frequency notch filter

2) Electromyography notch filter (center frequency: 35Hz)

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PCBs

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Amplitude-frequency Curve

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ECG of mine detected by the circuit