Amplifier

Question 1

Classification and comparison of signals

Answer 1

1) Periodic (sinusoidal) / Non-periodic (pulse)
2) Electric (Voice amplified through megaphone) / Non-electric (voice)
3) Analog (Audio) / Digital (Signal stored in code)

Question 2

Typical frequency and amplitude ranges of biological signals

Answer 2

• ECG, EEG, EMG, etc.
• ECG ranges between 0.1 - 500Hz and 70 microV - 5mV
• Intracellular voltage is 0 - 10KHz and 100 mV

Question 3

Positive and Negative Feedback amplifiers

Answer 3

If signal has same phase as input, Positive feedback:
- Higher amplification
- Lower transfer band
(E.g. Ultrasound)
If signal inverted, Negative feedback:
- Lower amplification (Gain)
- Higher transfer band
(E.g. All amplifier)

Question 4

Fourier-theorem for periodic and aperiodic signals

Answer 4

• Any signal can be decomposed as a sum of sinusoidal signals.
• Any signal can be constructed from sinusoidal components.
• If frequency range of signal is known, it can reconstruct signal without distortion.

Question 5

Parts and function of high and low pass filter circuits.

Answer 5

Function: Remove unwanted frequencies from the signal
Parts: Resistor and capacitor

Question 6

Digitization of analog signals

Answer 6

• Analog signals need to be converted to digital signals to be read and interpreted.
• ADC (analog digital converter)
• Reads many voltage at different times
• Must happen at same frequency as signal.

Question 7

Shannon-Nyquist theorem

Answer 7

For successful reconstruction of a signal, the frequency of sampling should be at least 2X higher than the highest frequency signal component (Overtone)

Question 8

Processing of pulse signals

Answer 8

Integral discrimination: Selecting signals higher than a certain amplitude.
Differential discrimination: Selecting signals with a defined range.