What is the common - mode rejection ratio (CMRR) of op amp lm358p?

Hey there! As a supplier of the op amp LM358P, I often get asked about the common - mode rejection ratio (CMRR) of this little but powerful component. So, let's dive right in and break it down.

First off, what's the CMRR? Well, in simple terms, CMRR is a measure of an op - amp's ability to reject common - mode signals. Common - mode signals are those that appear equally on both the inverting and non - inverting inputs of an op - amp. You don't want these signals to mess up your circuit's performance, right? That's where CMRR comes in. A high CMRR means the op - amp can distinguish between the differential signal (the one you actually care about) and the common - mode signal and ignore the latter.

Now, let's talk about the LM358P specifically. The LM358P is a dual operational amplifier that's widely used in various applications. It's known for its low power consumption, wide supply voltage range, and relatively low cost. These features make it a popular choice for many hobbyists and professionals alike.

The CMRR of the LM358P is typically specified in decibels (dB). A higher dB value indicates better common - mode rejection. For the LM358P, the typical CMRR value is around 70 dB at room temperature. But this can vary depending on a few factors.

One of the main factors that can affect the CMRR of the LM358P is the power supply voltage. As the supply voltage changes, the internal characteristics of the op - amp can shift, which in turn affects its ability to reject common - mode signals. Generally, a higher supply voltage can lead to a better CMRR, but this also means more power consumption.

Temperature is another important factor. As the temperature goes up, the performance of the LM358P can degrade. The CMRR might decrease, and the op - amp might become more susceptible to common - mode noise. That's why it's crucial to consider the operating temperature range when using the LM358P in your circuit.

So, why is CMRR so important in the LM358P? Well, in many applications, there are often common - mode signals present. For example, in audio circuits, there can be electromagnetic interference (EMI) that appears as a common - mode signal on the inputs of the op - amp. If the CMRR is low, this EMI can get amplified along with the desired audio signal, leading to poor sound quality.

Let's take a look at some applications where the CMRR of the LM358P really matters. In a Audio Transceiver, the LM358P can be used for signal conditioning. The audio signals coming in might have some common - mode noise due to the environment. A high CMRR ensures that this noise is minimized, and the clean audio signal is processed.

Another application is in sensor circuits. Many sensors output signals that are accompanied by common - mode noise. The LM358P can be used to amplify the differential signal from the sensor while rejecting the common - mode noise. This is crucial for accurate sensor readings.

Now, how does the CMRR of the LM358P compare to other op - amps? Let's take a look at the LM3886TF and LM324DR. The LM3886TF is a high - power audio amplifier. It has a relatively high CMRR, often in the range of 90 dB or more. This makes it a great choice for high - end audio applications where low noise is essential.

The LM324DR, on the other hand, is a quad operational amplifier. Its CMRR is similar to that of the LM358P, typically around 70 dB. However, the LM324DR has four op - amps in one package, which can be useful in applications where multiple amplification stages are required.

If you're thinking about using the LM358P in your project, there are a few things you can do to optimize its CMRR. First, make sure to use proper power supply decoupling. Adding capacitors between the power supply pins can help reduce power supply noise, which can improve the CMRR.

Second, pay attention to the layout of your circuit. Keep the traces for the inverting and non - inverting inputs as short and equal as possible. This can help minimize the introduction of common - mode signals due to electromagnetic coupling.

In conclusion, the CMRR of the LM358P is an important parameter that can significantly affect its performance in various applications. While it might not have the highest CMRR compared to some high - end op - amps, it offers a good balance between performance and cost.

If you're interested in purchasing the LM358P or have any questions about its CMRR or other technical specifications, feel free to reach out to me for a purchase negotiation. I'm here to help you make the best choice for your project.

References

• Texas Instruments LM358 datasheet
• Analog Devices application notes on op - amp common - mode rejection