Category Archive: Uncategorized
E&I had an excellent time at the WPTC in London! Very exciting progress being made in wireless power transfer. Notice the nice blue amp in the pic?
Posted by: Jeff Keller, July 2, 2019
E&I is excited to be exhibiting next week in Spain for the ISTU- EUFUS Symposium. Please stop by booth # 15 to find out what’s new!
E&I exhibited at the IEEE IUS conference again this year. The conference was held in Kobe, Japan and there were approximately 1,400 attendees many of whom stopped by our booth to see our new S-Series product and to discuss their applications. It is always great to meet with potential new customers and visit with our current customers. We are looking forward to exhibiting at the conference next year which will be held in Glasgow, Scotland.
As always, E&I can help with all your RF power needs, especially with regards to ultrasound!
We often hear tales of the experiments that are conducted by scientists. Behind closed doors, in their laboratories in the depth of night. Bunsen burners heating flasks of overflowing foam as test tubes containing varying concoctions are added. A Van De Graff generator in the background is driving the voltage of a couple of parallel plates to breakdown and sparks fly across them sizzling and piercing the silence. The crazy scientist wearing a well-worn and chemical-stained lab coat looks on with wild scary glazed eyes. Rapidly recording notes into an overstuffed lab book, their hair all standing on end, with a smile reminiscent of Mona Lisa.
However, if you meet Jessica Foley, the Chief Scientific Officer at the Focused Ultrasound Foundation, you will find, on first impression at least, that she does not live up to the caricature at all. She is very engaging and she and her colleagues were very generous with their time as we discussed E&I and where our amplifiers fit into the FUS environment.
Then just as we were about to leave, she said “I must tell you of an experiment that I did with one of your amplifiers, whilst I was at the University of Washington.” (Oh yeah; here we go I thought.) “Late one afternoon” she said “myself and some other researchers locked the door of the lab and using one of your high power amplifiers decided to try some acoustic cooking. We immersed salmon, vegetables and steak into water and then applied several hundred watts of RF power to the transducers and cooked all the food with ultrasonic energy.” She went on to tell us that it all tasted wonderful, though she herself avoided the steak that was well done in the middle and rare on the outside!
So it is true that you never know what crazy scientists will cook up!
Written by Tony Harris, October 5, 2017
Written by Tony Harris, September 22, 2017
Don’t you think the quality of car sound systems today is quite phenomenal? They are very compact units and capable of high volume and low distortion. How do they do it? You’d think you’d have to lug a trailer on the back full of amplifiers to get that type of sound quality.
The fundamental components that are doing the work in today’s amplifiers are transistors. The transistor gets its name from the combination of ‘resistor’ and ‘trans’. Basically it is just a resistor that we can vary. We can vary it from a short circuit to an open circuit. If you recall from some science or physics class years ago, you will know that the loss in a resistor is I2R: where I is the current in Amps and R is the resistance in Ohms. So if the resistance is 0 then the loss is the current squared times zero, so it’s zero loss. Now if the resistance is open (infinite) then no current can flow so again the loss is zero. So if we use a transistor in only two states; open or short, there is no loss and therefore, very efficient.
Car sound systems use a type of sampling technique, whereby they sample the input signal and effectively digitize it. Then they amplify it, but because they are now amplifying a digital signal it is either full on or full off – very efficient. After it is amplified they use a filter to reconstruct the analogue signal. The end result is it sounds great, but is very efficient so doesn’t dissipate a lot of heat and can be very small.
So why don’t we use this technique for high frequency amplifiers for ultrasonic and communication applications? The difficulty with this technique is that you have to switch the amplifier much faster than the frequency of the signal that you are amplifying. For audio signals this is not a problem but as we move into the high KHz and MHz region this pushes the state of the art of the capability of the transistors.
However, here at E&I using fast devices and interleaving techniques, we are pushing the frequencies higher and higher. We have our 1000S04 which is capable of 1000 watts of instantaneous power from 10 KHz up to 400 KHz. We also have 500S06 which is capable of 500 Watts 20 KHz to 600 KHz.
Before the end of June we will be at 1 MHz and then go beyond.
E&I is the leader in this technology, which will become the standard for ultrasound systems.
Written by Tony Harris, 2nd September 2017
Someone was asking me the other day; how we are able to get such high switching rates on the large Fets that we use in our S-Series to enable us to achieve 1000 watts over a 600 KHz bandwidth. It is a good question, if you look at the performance of linearity, bandwidth and flatness you think that we were switching at over 3 MHz. Actually, in the 1000S04 we only switch at 1.6 MHz. But, then we use the technique, common in switch mode power supply design, to interleave the two halves of the H bridge. This enables us to mimic the performance that one would expect by from switching at 3.2 MHz.
So that’s the secret. We are looking to interleave in quadrature and so further push the frequency while maintain the excellent linearity and harmonic performance.
Written by Tony Harris, February 8, 2017
The value of note taking and retention of documents is severely reduced if one is unable to locate the information at a later date. We are lazy these days, I fear. With the advent of “search” applications we just type a few words into our PC and hit enter. Seemingly, miraculously, relevant documents are unearthed. And so our filing systems have become all but redundant. I have pieces of paper that collect upon my desk and when they have reached an amount that I find annoying, I file them. I do this by sorting them into two groups. The first I unceremoniously dump into the shredder, and the second I simply stuff into a manila folder – mark it “Important and Confidential” and shove it into a filing cabinet in my office. This works very well for the retention of documents. But it leaves a lot to be desired with respect to the retrieval aspect and so calls into question the value of the whole activity in the first place. Of course, as I file said documents, I am convinced that I shall remember where they are. But then in actuality, when I try to find something, the fact that I know of their existence only increases my frustration. I get incensed as I randomly and fruitlessly pull out filing drawers, folders and documents and then vacillate between the scanning and perusal of page after page.
But I did take refuge in the belief that this was a universal problem with varying solutions all based on the effort and time that one puts into maintaining a system. Jan, my wife, for example files all the required documents for taxes, insurance, appliance operating manuals and is able to locate them as required. Although I do not have the necessary skill set to perform this task, it is a fairly simple set theory problem, with well defined labels.
The other day, I was asked a question by a customer in Australia as to the IMD performance of E&I amplifiers with 12 tones at 2 watts per channel. I was fairly sure that I did not have any information on how to glean this data from our test records and after a quick Google search left me empty-handed I decided to ask Serge Juhel, an old colleague of mine for help. I say old colleague as I have known him for a long time and he is old. Serge came to the rescue with the calculation of PEP and the recommended CW power required. In addition to attaching a document delineating the test procedure, he also copied an old colleague of ours, John Pritiskutch (yes; we’ve known him for a long time and he’s old) and asked him to verify the calculations and check the formulae. John kindly did this but noted his surprise that we were having this discussion as Serge had previously authored a document which I was copied on, that explains the calculations in detail. John had thoughtfully attached a copy of this document to his e-mail.
The document that John attached was a scan of a print out of an e-mail that Serge had sent me in 1992.
This is 2017! What sort of archival system does John have? The question was about multi-tone IMD performance v two-tone measurement. What can you file that under and be able to retrieve it??? Remember, this is a paper system. The document he sent me was scan of a print out. The print out was from a “dot matrix’ printer!
So in conclusion; I’d say, if you are looking for the answer to an RF question ask Serge Juhel; he probably can answer it without looking for notes. Or ask John Pritiskutch, he also can probably answer without looking for notes, but if he needs to – he has them!
Written by Tony Harris, November 17, 2016
Anyone involved in RF design or testing in the field of ultrasound, telemetry activation, HF, VHF or UHF applications knows E&I®. Over the last 13 years, picking up where ENI® left off, we have been supplying the industry with rugged and reliable broadband power amplifiers.
They will not be the lightest piece of test equipment on your bench, nor indeed the quietest. They will probably be your bluest and also the most rugged and reliable piece of gear. They are indeed known throughout the industry as the stalwart solution for your RF testing needs.
About six years ago, at the behest of several customers, we began supplying RF modules. This enabled our customers to utilize our superior technology and proven designs as an integral part of their systems. Working with these customers we have found that to in order to provide the optimum RF solution, it preferable to begin working with them, as an extension of their design team, early on in the OEM project.
We have therefore launched a new division; called the E&I OEM Solutions Division. The charter of this new group is to work with clients to define their RF needs and assist in architecting the clients system, to bring the RF issues to the forefront and so avoid wasted time and effort in unnecessary design cycles. Then, utilizing the technology and expertise of E&I’s engineering group provide an optimum OEM solution.
To learn more about E&I’s OEM Solutions Division and how you can utilize the group as an extension of your design team, give me a call or drop me an e-mail.
Tony Harris (November 17, 2016)
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.
Written by Tony Harris, August 18, 2016
Spectrum: The word is derived from the Latin word to look and was used describe an image or ghost. The word spectrum was first used, by Isaac Newton, in the field of optics to refer to the output of a prism. Such as the one depicted on Pink Floyd’s “Dark Side of The Moon” album. Good album that, alas I digress. Soon the term expanded to apply to other waves that could be measured as a function of frequency. For example sound waves and all types of electromagnetic waves. It later became used to describe any continuum.
So when we talk about spectral analysis we are referring to a measurement of some function along a continuous variable. A spectral analysis of a rainbow for example would consider the intensity of light as a function of the colors present. If we did a spectral analysis of someone’s speech we would find that certain frequencies were more common than others.
Mass Spectrometry is name given to a technique that allows us to identify materials by analyzing their mass to charge ratio. Mass spectrometry was invented at the University of Birmingham by Francis Aston. He received the Nobel Prize in Chemistry for his invention in 1922. My father worked on the mass spectrometer at the University of Birmingham in the mid-1940’s but he didn’t get a Nobel Prize.
In its simplest form a mass spectrometer uses an electric field to accelerate ions and then uses a magnetic field to deflect them. Depending upon the ratio of the electric charge to the mass, the ions will be separated and so can be identified by their mass/charge ratio. One type of mass analyzer used in mass spectrometry is a quadrupole. Here an rf (radio frequency) signal is applied to four conductors. As the ions travel through the quadrupole the electric field set up by the rf signal will cause ions with a specific mass/ charge ratio to reach the detector.
Matt Brantley of Baylor University presented a poster at the ARMS conference in San Antonio, Texas earlier this year entitled: A Modular Data Station for Radio-Frequency Ionization FT-ICR Mass Spectrometry Imaging. We were pleased to work with Matt on the Amplifier and balun circuitry for his quadrupole. These studies facilitate metabolomics, the understanding of metabolism and the drugs that can help support it. We are excited to be part of this research.
Tony Harris August 2016