Consider a bioinstrumentation amplifier interfacing with electrodes to measure a biopotential signal originating from the body....

 

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Consider a bioinstrumentation amplifier interfacing with electrodes to measure a biopotential signal originating from the body. The voltage signal picked up by the electrodes, placed in direct contact with the skin, is subject to 6 μV root-mean-square amplitude of additive noise due to the electrode-skin interface. The amplifier has a sensitivity of 2,000 over its linear range, with output ranging from -2.5V to +2.5V, and saturates with zero sensitivity outside of this range. The amplifier has an input-referred offset of -120 μV. The amplifier output is converted to digital samples, at 2 kHz sampling rate, by an analog-to-digital converter (ADC) with 10-bit resolution covering the entire -2.5V to +2.5V output range of the amplifier. (a) Find the accuracy, precision, and resolution of the biopotential signals measured by the instrument. Compare the three, and explain the differences. (b) Find the range of biopotentials over which the instrument produces a valid measurement. How can you detect whether the biopotential signal is outside of this range? (c) What is the maximum frequency of biopotential signals that can be reconstructed from its samples produced by the ADC, and what happens to a signal above that frequency? Illustrate what you would observe at the digital output when you present the amplifier input with a 200 µV peak-to-peak sine wave signal of frequency 1.9 kHz. Consider a bioinstrumentation amplifier interfacing with electrodes to measure a biopotential signal originating from the body. The voltage signal picked up by the electrodes, placed in direct contact with the skin, is subject to 6 μV root-mean-square amplitude of additive noise due to the electrode-skin interface. The amplifier has a sensitivity of 2,000 over its linear range, with output ranging from -2.5V to +2.5V, and saturates with zero sensitivity outside of this range. The amplifier has an input-referred offset of -120 μV. The amplifier output is converted to digital samples, at 2 kHz sampling rate, by an analog-to-digital converter (ADC) with 10-bit resolution covering the entire -2.5V to +2.5V output range of the amplifier. (a) Find the accuracy, precision, and resolution of the biopotential signals measured by the instrument. Compare the three, and explain the differences. (b) Find the range of biopotentials over which the instrument produces a valid measurement. How can you detect whether the biopotential signal is outside of this range? (c) What is the maximum frequency of biopotential signals that can be reconstructed from its samples produced by the ADC, and what happens to a signal above that frequency? Illustrate what you would observe at the digital output when you present the amplifier input with a 200 µV peak-to-peak sine wave signal of frequency 1.9 kHz. Consider a bioinstrumentation amplifier interfacing with electrodes to measure a biopotential signal originating from the body. The voltage signal picked up by the electrodes, placed in direct contact with the skin, is subject to 6 μV root-mean-square amplitude of additive noise due to the electrode-skin interface. The amplifier has a sensitivity of 2,000 over its linear range, with output ranging from -2.5V to +2.5V, and saturates with zero sensitivity outside of this range. The amplifier has an input-referred offset of -120 μV. The amplifier output is converted to digital samples, at 2 kHz sampling rate, by an analog-to-digital converter (ADC) with 10-bit resolution covering the entire -2.5V to +2.5V output range of the amplifier. (a) Find the accuracy, precision, and resolution of the biopotential signals measured by the instrument. Compare the three, and explain the differences. (b) Find the range of biopotentials over which the instrument produces a valid measurement. How can you detect whether the biopotential signal is outside of this range? (c) What is the maximum frequency of biopotential signals that can be reconstructed from its samples produced by the ADC, and what happens to a signal above that frequency? Illustrate what you would observe at the digital output when you present the amplifier input with a 200 µV peak-to-peak sine wave signal of frequency 1.9 kHz.