Introduction

The Analog Signal Conditioning (OPAMP) peripheral features up to three internal operational amplifiers (op amps). It can help reduce or eliminate the need for external/discrete op amps in electronic designs, thus potentially decreasing the bill of materials. The main purpose of op amps is to condition the analog signals before the acquisition (and further digital processing) in a microcontroller or to provide the necessary output drive in control applications.

This technical brief describes how the analog signal conditioning block (OPAMP) part of the AVR® DB MCU devices works. It starts by describing the simplest configuration upon which more complex ones are built. The topologies of interest are as follows:

• Op amp connected directly to pins:

  The simplest and most basic configuration offering the highest degree of flexibility, with external connections and components.

• Voltage Follower or Unity Gain Buffer:

  A common configuration for converting a high impedance input to a low impedance output.

• Non-Inverting Programmable Gain Amplifier:

  Programmable gain signal amplification via the internal feedback resistor network.

• Differential Amplifier using two op amps:

  Differential input voltage amplification with a rejection of the common-mode voltage.

• Instrumentation Amplifier using three op amps:

  Differential signal amplification with high input and low output impedance.