E&I’s New S Series RF Amplifiers

Written by Tony Harris, August 25, 2016


You may have heard of Class D RF amplifiers, you may have heard of Class S RF amplifiers and you may have heard differing definitions of both. There seems to be a lot of confusion on the subject. Depending upon whether you come from the audio world or the RF world you will probably hold opposing views of which is correct.

Far be it from me to get embroiled in such a messy discussion. E&I is launching a series of amplifiers, some that operate in Class D and some that operate in Class S. But we’re not saying which is which to avoid getting ensconced in the argument and having pocket protectors thrown at us.

So there are two types of amplifiers; one is a ‘Sampling’ type, that can be broadband and can operate from DC up to about 1/5th of the Nyquist frequency and the other is a ‘Switching’ amplifier that is narrow band and operates at the switching frequency. So we call them our S-Series of amplifiers and dodge the all important question.

We are fortunate that our lead design engineer on the project, Bill Pulhamus, has that all important combination of talent and experience. What is exciting is that using this technology he has been able to keep the integrity of Class A performance and yet achieve 90% efficiency. This means that we are able to produce an amplifier that is much smaller and at a much lower cost.

The first one of our S-Series to go into production is of the ‘Sampling’ type which means that it also offers wide bandwidth. It produces 1,000 watts from 20 – 200 KHz and is in a 2U rack mount form factor. We will be releasing further models later in the year as we push the frequency up.


Tony Harris

August 2016



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