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university:courses:electronics:electronics-lab-heartbeat [25 Jan 2022 08:00] – Remove SIMetrix files Monica Ignat | university:courses:electronics:electronics-lab-heartbeat [30 Jan 2023 09:19] (current) – [Preamplifier] Antoniu Miclaus |
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The input signal from the heartbeat measurement setup is fed into a Differentiator Amplifier Circuit(([[http://www.electronics-tutorials.ws/opamp/opamp_7.html|Differentiator Amplifier]])) (C<sub>1</sub>, A<sub>1</sub>, R<sub>3</sub>). The capacitor blocks any DC content, C<sub>1</sub> and R<sub>3</sub> behaving as a high pass filter with the cut-off frequency F<sub>c1</sub> being determined by the following formula: | The input signal from the heartbeat measurement setup is fed into a Differentiator Amplifier Circuit(([[http://www.electronics-tutorials.ws/opamp/opamp_7.html|Differentiator Amplifier]])) (C<sub>1</sub>, A<sub>1</sub>, R<sub>3</sub>). The capacitor blocks any DC content, C<sub>1</sub> and R<sub>3</sub> behaving as a high pass filter with the cut-off frequency F<sub>c1</sub> being determined by the following formula: |
<WRAP centeralign><m>F_c1=1/{2 pi R_1C_1}</m></WRAP> | <WRAP centeralign><m>F_c1=1/{2 pi R_3C_1}</m></WRAP> |
Besides filtering, this stage serves also as an amplifier taking as input the current (I<sub>A1</sub>), and generating at the output an inverted voltage (V<sub>A1</sub>) based on the negative feedback resistance (R<sub>3</sub>): | Besides filtering, this stage serves also as an amplifier taking as input the current (I<sub>A1</sub>), and generating at the output an inverted voltage (V<sub>A1</sub>) based on the negative feedback resistance (R<sub>3</sub>): |
<WRAP centeralign><m>V_A1=-I_A1*R_1</m></WRAP> | <WRAP centeralign><m>V_A1=-I_A1*R_3</m></WRAP> |
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====Active Low-Pass Filter=== | ====Active Low-Pass Filter=== |