This document discusses various types of biological amplifiers. It notes that biological signals have low amplitude and frequency, so amplifiers are needed to increase their amplitude. A good bio-amplifier should have low output impedance, be free from drift and noise, and have high common mode rejection. It describes several types of bio-amplifiers - differential, operational, instrumentation, chopper, and isolation amplifiers. Isolation amplifiers provide protection against electrical shock by using transformer, optical, or capacitive isolation. The document gives examples of how these amplifiers can be applied to ECG and other biological signal measurement.

1. Disaster Management
Prepared by
S.KARTHIKKUMAR M.E.,(Ph.D)
AP/EEE
JAI SHRIRAM ENGINEERING
COLLEGE,TIRUPUR

2. Need for Bio-amplifier:
 Generally, biological/bioelectric signals have low
amplitude and low frequency. Therefore, to
increase the amplitude level of biosignals
amplifiers are designed.

3. Basic Requirements for
Biological Amplifiers
 A bio-amplifier should have a small output
impedance.
 A good bio-amplifier should be free from drift and
noise.
 Common Mode Rejection Ratio (CMRR) value of
amplifier should be greater than 80dB to reduce the
interference from common mode signal.

4. Types of Bio Amplifiers
 Differential Amplifier
 Operational Amplifier
 Instrumentation Amplifier
 Chopper Amplifier
 Isolation Amplifier

5. Voltage and Frequency ranges of Some
common Bio potential Signals:
ECG

6. Differential Amplifier

7. Op-amp Differential Amplifier:
R1

8.  These amplifiers are applied for the construction of ac
or dc amplifiers, active filters, phase inverters,
multivibrators and comparators, etc. by suitable
feedback arrangement, and therefore find a large
number of applications in the medical field.

12. Inverting Amplifier:
V 1

13. Non-Inverting Amplifier:

15. Impedance matching circuit:
Instrumentation Amplifier:

16. Isolation Amplifier:
 For safety, it is important to protect the user from the hazards of
electrical shock. Electrical shock can always present a safety risk with
electrical circuits and it is important to consider the problem seriously.
 It is worth highlighting that it is current, not voltage, which is the real
hazard here. Current flow in tissue can cause excessive resistive
heating, leading to bu
 rns, electrochemical heating, and electrical stimulation of
neuromuscular systems.
 Isolation amplifiers can be used to break ground loops, eliminate
source ground connections, and provide isolation protection to patient
and electronic equipment.

18. Three methods are used in the
design of isolation amplifiers:
 (i) transformer isolation
 (ii) optical isolation
 (iii) capacitive isolation.


22. ECG Isolation Amplifier

24. Right Leg driven ECG
amplifier:

25. RL
up amp

26.  Thank you