Transimpedance (Gm) Amplifier

The following figure of a circuit shows a transimpedance (Gm) amplifier as formed by an MCP6XXX op amp and R₁. It converts the sensor current (I_SEN) to a voltage. The capacitor C₁ is sometimes needed to stabilize the amplifier when the source has a large capacitance.

Advantages:

• Good impedance buffering of source
• Simplicity

Disadvantages:

• Design may need to be stabilized

Sensor Examples:

• IR smoke detector
• Photodiode
• Photodetector

​Learn More

• Sensor Overview
• Microchip op amp product page
• Smoke Detector, CO Detector and Horn Driver ICs
• MCP6031 Photodiode PICtail™ Plus Demo Boar