instrumentationVerstärkern

Instrumentation amplifiers, often abbreviated as in-amps, are a type of differential amplifier designed for use in measurement and control systems. They are characterized by their high common-mode rejection ratio (CMRR), high input impedance, and low input offset voltage. These properties make them ideal for amplifying small differential signals that are often corrupted by common-mode noise.

The core of an instrumentation amplifier typically consists of three operational amplifiers. Two of these are non-inverting amplifiers, each with a single resistor setting the gain. The third op-amp, configured as a differential amplifier, sums the outputs of the first two. A key advantage is that the input impedance is determined by the input resistors of the first two op-amps, which are typically very high, preventing loading of the signal source. The overall gain is usually set by a single external resistor, simplifying gain adjustments.

Instrumentation amplifiers are crucial in applications where precise measurement of low-level signals in the presence of significant common-mode voltages is required. Examples include thermocouple measurements, strain gauge bridges, medical instrumentation (like ECG machines), and audio processing. Their ability to accurately amplify small differences while rejecting unwanted common signals contributes significantly to signal integrity in sensitive electronic circuits. The high CMRR ensures that any voltage present on both input terminals equally is effectively canceled out, leaving only the desired differential signal to be amplified.