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Programmable Gain Amplifier

Last modified by Microchip on 2023/11/09 09:03

The circuit below shows an MCP6SX2 Programmable Gain Amplifier (PGA) used to condition multiple sensors. The PGA allows the user to select an input sensor and gain with the Serial Peripheral Interface (SPI) bus. It can also help linearize non-linear sensors, e.g. thermistors.

Programmable gain amplifier circuit

Advantages

Multiple sensors
Complementary Metal Oxide Semiconductor (CMOS) input (high impedance and low bias current)
Digital control (SPI) of input and gain
Linearization of non-linear sources

Disadvantages

Input stage distortion
Amplifies common mode noise
Needs Microcontroller Unit (MCU) and firmware

Sensor Examples

Thermistor with a voltage divider to convert resistance to voltage
Thermopiles
Piezo-electric film

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