3 different types of isolation amplifiers are explained...

2.  Isolation
amplifiers provide electrical isolation
and an electrical safety barrier.
 They protect the patients from leakage
currents.
 They break the ohmic continuity of electrical
signals between input and output.
 Isolated power supplies are provided for both
the input and output stages.
 Used to amplify low level signals.

4. Three types of methods are used to design isolation
amplifier



Transformer isolation
Optical isolation
Capacitive isolation

6. It uses either frequency modulated or a pulse
width modulated carrier signal.
 Internally it has 20KHz oscillator, transformer,
rectifier and filter to provide supplies for each
isolated stages.
 Rectifier- input to primary OPAMP.
 Transformer- couples the supply.
 Oscillator – input to secondary OPAMP.
 A low pass filter is used to remove the other
frequency components.


7. 


High common mode rejection ratio
High linearity
High accuracy

9.  MEDICAL
Patient Monitoring and Diagnostic
Instrumentation
 INDUSTRIAL
Ground Loop Elimination and
Off-ground Signal Measurement
 NUCLEAR
Input/output/Power Isolation

11.  The
biological signal is converted into a light
signal by LED for further process.
 It has patient circuit which is the input circuit
and a phototransistor which forms the output
circuit.
 Each circuit is battery driven.
 The input circuit converts the signal to light
and the output circuit converts the light back to
signal.

13. Original frequency and amplitude is obtained.
 High linearity.
 No modulator or demodulator is needed as it
couples optically.
 Improves patient safety


14.  INDUSTRIAL PROCESS
CONTROL
 DATA ACQUISITION
 INTERFACE
ELEMENT
 BIOMEDICAL MEASUREMENTS
 PATIENT MONITORING
 TEST EQUIPMENT
 CURRENT SHUNT MEASUREMENT
 GROUND-LOOP ELIMINATION
 SCR CONTROLS

16. It uses digital encoding of the input voltage and
frequency modulation.
 The input voltage is converted to proportional
charge on the switched capacitor.
 It has modulator and demodulator circuits.
 The signals are sent across a differential capacitive
barrier.
 Separate supplies are given for both sides.


18. Ripple noises are removed.
 It avoids device noise, radiated noise and
conducted noise.
 High immunity to magnetic noises.
 Useful for analog systems.
 Has high gain stability and linearity.


19. 




DATA ACQUISITION
INTERFACE ELEMENT
PATIENT MONITORING
ECG
EEG

20. 


Commonly used
Transformer isolation amplifier
Cost
Optical- low cost due to less components
Transformer
Capacitor coupled- high cost
Isolation voltage
Optical- low (800V)
Transformer- medium (1200V)
Capacitance- high (2200V)

21. 

Isolation resistance
Optical- 10^12
Transformer- 10^10
Capacitance- 10^12
Gain stability and Linearity
Optical- 0.02%
Transformer- between 0.005% and 0.02%
Capacitance- 0.005% (best)