Instrumentation Amplifiers
The circuit below shows an instrumentation amplifier that conditions a remote voltage sensor. The input resistors provide isolation and detection of the sensor open-circuit failure. It amplifies the input difference voltage (VSEN+ - VSEN-) and rejects common mode noise.
Advantages:
- Excellent rejection of common mode noise, e.g. great for remote sensors
- Resistive isolation from the source
- Detection of sensor failure
Disadvantages:
- Resistive loading of the source
- Higher cost
Sensor Examples:
- Remote thermocouple
- Remote Resistive Temperature Detector (RTD) (with a current source or voltage divider to produce a voltage from the RTD)
- Wheatstone Bridge