{"id":6900,"date":"2023-01-06T13:35:43","date_gmt":"2023-01-06T18:35:43","guid":{"rendered":"https:\/\/audioapartment.com\/?p=6900"},"modified":"2023-06-11T12:33:21","modified_gmt":"2023-06-11T16:33:21","slug":"what-is-amplifier-slew-rate","status":"publish","type":"post","link":"https:\/\/audioapartment.com\/techniques-and-performance\/what-is-amplifier-slew-rate\/","title":{"rendered":"What Is Amplifier Slew Rate? (Answered)"},"content":{"rendered":"\n

As audio equipment becomes more advanced, it’s important to have an understanding of what an amplifier slew rate is<\/strong>. This term is typically used in conjunction with high-end audio equipment and defines the maximum frequency at which an amplifier can output power.<\/p>\n\n\n\n

This article will cover amplifier slew rate, what causes slew rate, and how to measure it. So, if you’re in the market for an amplifier, it’s important to know the maximum frequency that the amplifier can handle. This information can help you make an informed decision about which amplifier is right for you.<\/p>\n\n\n\n

What is the amplifier slew rate? <\/strong>The slew rate is the rate at which its output voltage may fluctuate, and it is measured in volts per microsecond. The slew rate of an operational amplifier is determined by introducing a big signal step, say one volt, to its input and then observing how quickly the output signal’s amplitude changes from 10% to 90%.<\/p>\n\n\n\n

What is an amplifier slew rate?<\/h2>\n\n\n\n

“Slew rate” refers to the rate at which an electrical quantity, such as voltage or current, changes over a certain period. <\/strong>For example, the slew rate of an amplifier (or another signal processor) is the rate at which the signal is changed (distorted). As a result, some lag may be seen between input voltage changes (both slow and rapid) and their manifestation at the output.<\/p>\n\n\n\n

The dynamics (and especially the transients) of the audio waveform are negatively impacted by this distortion<\/strong>, which is, in fact, the case. However, slew rate really has a greater impact on high-frequency clarity in practice.<\/p>\n\n\n\n

How can you measure the amplifier slew rate of your audio equipment?<\/h2>\n\n\n\n

The slew rate can be calculated by providing a step signal to the op-input amp’s stage and monitoring the rate at which the output signal changes from 10% to 90% of its amplitude. The applied step signal is typically about 1 V in magnitude.<\/p>\n\n\n\n

Using the output voltage waveform, we can calculate the slew rate. The slew rate may be determined using an oscilloscope and a function generator<\/strong>.<\/p>\n\n\n\n

What causes the slew rate?<\/h2>\n\n\n\n

In general, the phenomenon of slew rate derives from two properties of op-amp dynamic response. First, the output amplifiers<\/a> will not immediately reflect a shift in the input. Accordingly, there will always be a lag between modifying the input and seeing the resulting effect.<\/p>\n\n\n\n

Second, this delay may cause a significant discrepancy between the voltages delivered<\/strong> to the inverting input terminal and the non-inverting input terminal when an op-amp is coupled in a negative-feedback setup. <\/p>\n\n\n\n

The behavior of the differential-pair input stage is altered by such a huge differential voltage, leading to linear growth (or decay) in the output voltage, as shown by VOUT(t) = SRt. The quantity of compensating capacitance significantly impacts the slew rate (SR).<\/p>\n\n\n\n

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Image of a black amplifier on top of a wooden surface. Source: akshar dave, pexels<\/figcaption><\/figure>\n\n\n\n

Practical amplifier slew rates<\/h2>\n\n\n\n

It is well known that an amplifier’s slew rate significantly impacts <\/strong>signal distortion above a certain frequency. Even budget amplifiers should have a slew rate greater than 6.3 V\/s.<\/p>\n\n\n\n

The high slew rates often seen in amplifiers are the result of careful design. In order to effectively remove any possible mistakes and undesired distortion, the slew rate should produce a maximum frequency beyond the hearing range<\/strong>.<\/p>\n\n\n\n

Remember that there are many additional potential sources of distortion. A slow slew rate should not be one of them. To get rid of the high-end frequencies that aren’t audible to humans, many amplifiers apply a low-pass filter to the audio stream. Why bother amplifying them if we can’t hear them?<\/p>\n\n\n\n

…we may further protect ourselves from distortion caused by slew rate by lowering or eliminating the ultrasonic frequencies in the stream.<\/p><\/blockquote><\/figure>\n\n\n\n

Even if it’s debatable to do so, we may further protect ourselves from distortion caused by slew rate by lowering or eliminating the ultrasonic frequencies in the stream.<\/p>\n\n\n\n

In addition, the output at high frequencies is optional for actual audio transmissions for our listening experience. In a well-balanced audio mix<\/a>, the brightness range (arguably 6 kHz to 20 kHz) actually needs less power than the lower frequencies.<\/p>\n\n\n\n

If you want even more tips and insights, watch this video called “Operational Amplifier Slew Rate | Op Amp Slew Rate”<\/em> from the ElectronicsNotes YouTube channel.<\/p>\n\n\n\n

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