What is operational amplifier? Define the terms slew rate and CMRR.

Operational Amplifier

An operational amplifier (op-amp) is a high-gain electronic voltage amplifier with a differential input and, usually, a single output. Operational amplifiers are widely used as comparators, summing amplifiers, integrators, and differentiators.

The op-amp is a versatile device that can be used to amplify, add, subtract, integrate, and differentiate signals. It is a key component in many electronic circuits, including amplifiers, filters, and oscillators.

Slew Rate

The slew rate of an op-amp is the maximum rate at which its output voltage can change. It is typically measured in volts per microsecond (V/µs). The slew rate is limited by the op-amp's internal circuitry, and it can be affected by the op-amp's gain, the frequency of the input signal, and the load capacitance.

CMRR

The common-mode rejection ratio (CMRR) of an op-amp is the ratio of the differential gain to the common-mode gain. It is typically measured in decibels (dB). The CMRR is a measure of the op-amp's ability to reject common-mode signals, which are signals that appear on both input terminals.

Mathematically, CMRR is defined as:

$$ CMRR = 20 \log_{10} \left( \frac{A_{d}}{A_{cm}} \right) $$

where:

• CMRR is the common-mode rejection ratio in decibels (dB),
• $A_d$ is the differential gain of the op-amp,
• $A_{cm}$ is the common-mode gain of the op-amp.

A high CMRR is desirable in op-amps because it reduces the effects of common-mode noise and interference.

Conclusion

The operational amplifier is a versatile and widely used electronic device. Its high gain and differential input make it ideal for a variety of applications, including amplifiers, filters, and oscillators. The slew rate and CMRR are important op-amp parameters that must be considered when selecting an op-amp for a particular application.