Application Note

Using Digital Potentiometers For Programmable Amplifier Gain

Source: Microchip Technology Inc.

Usually a sensor requires its output signal to be amplified before being converted to a digital representation. Many times an operational amplifier (op amp) is used to implement a signal gain circuit. The programmability of this type of circuit allows the following issues to be solved:

  • Optimization of the sensor output voltage range
  • Calibration of the amplifier circuit’s gain
  • Adapting gain to input signal variations
    • sensor characteristics change over temperature/voltage
    • multiple input sources into a single gain circuit
  • Field calibration updates
  • Increased reliability vs mechanical potentiometer
  • BOM consolidation – one op amp and one digital potentiometer supporting the various sensor options