Two large microfarad (F) capacitors are used in the input of the op-amp in the PPG circuit.

Two large microfarad (μF) capacitors are used in the input of the op-amp in the PPG circuit. What is the magnitude of the impedance of the large capacitor connected to the phototransistor for our targeted signal frequency range (i.e.heart rate normally varies from ~ 40 –200 bpm in humans)?

How does the impedance of this capacitor compared to the other resistors also connected to the op-amp input terminal (+)? What would be the impedance of this capacitor for DC input signals, such as the nearly non-varying light of the room environment (i.e.frequency ~ 0 Hz)? Describe the function of these capacitors

How does the fundamental frequency of our targeted pulse signal (i.e.largest expected pulse rate is 200 bpm) compare with the Nyquist frequency? How does the cut-off frequency for our filter compare to the pulse frequency range? Why would we want a cut-off frequency higher than the maximum pulse rate?

Transcribed Image Text:

+5V, +5V, +5V, +5V, 100 nF 100 0 1 kn 470 ka OP27 1 µF To DAQ input 100 kn 100 nF 1 MO QSD123 phototransistor 1 k2 10 uF IR-LED „QSD123 +5V, +5V, +5V, +5V, 100 nF 100 0 1 kn 470 ka OP27 1 µF To DAQ input 100 kn 100 nF 1 MO QSD123 phototransistor 1 k2 10 uF IR-LED „QSD123

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Answer The impedance or reactance of capacitor decreases as ... View the full answer