Introduction AD620 Instrumentation Amplifier

What is an Instrumentation Amplifier?

• An instrumentation amplifier is a differential amplifier which meets certain industry standard requirements. They are :

Precise low level signal amplification Low noise Low thermal drift High input resistance Accurate closed loop gain and easier gain adjustment Low power dissipation High CMRR High slew rate

What are the needs of Instrumentation amplifier?

• In many industrial and consumer applications the measurement and control of quantities such as temperature, pressure and humidity etc are required.

• A transducer converts these quantities into proportional electrical signal first

• Output of the transducer is then applied to an amplifier called “Instrumentation amplifier”

• The amplifier amplifies the low level output signal of the transducer to such a level that it can be drive the indicator or display

AD 620 IC

Manufactured by Analog Devices company Industry standard Low cost and high accuracy Instrumentation amplifier

Pin Diagram of AD620

Here, RG – External Gain setting Resistor

Block diagram of AD620

Features• Easy to use• Gain can be set with one external resistor(Gain range 1 to

10000)• Wide power supply range (0 to 18)• Higher performance• Low cost as compared to other instrumentation amplifiers• Low noise• Bandwidth is more• High common mode rejection ratio(about 100dB)• Available in 8 lead package• Low offset voltage• Low input bias current

Applications

• Pressure measurement• Medical ECG• Precision V to I converterAnd many more

OP 177 opamp IC

• It is ultra high precision operational amplifier IC of any opamp currently available

• Available in 8 pin DIP package

Pin diagram of OP177

Features of op177

• Ultra low offset voltage (20 micro volt at room temp)

• Excellent open loop gain• High CMRR (130dB)• Low supply current• Low noise• High slew rate and high bandwidth• Supply voltage (-22 to +22v)• Low power dissipation

Applications of op177 opamp

• Thermocouple amplifiers • Precision high gain amplifiers• In bilateral current sources• Precision positive peak detectors• Precision threshold detector• Precision value amplifiers• Isolation of large capacitive loads