Welcome to PowerUP, a podcast show hosted by Maurizio Di Paolo Emilio that brings life to some of the stories on power electronics technologies and products featured on powerelectronicsnews.com and through other AspenCore Media publications. In this show, you’ll hear both engineers and executives discuss news, challenges, and opportunities for power electronics in markets such as automotive, industrial, and consumer. Here is your host, editor-in-chief of powerelectronicsnews.com and eeweb.com, Maurizio Di Paolo Emilio.
歡迎收聽由Maurizio Di Paolo Emilio主持的podcast節目Powerup。本節目為PowerElectronicsNews.com和其他AspenCore Media旗下網站的內容帶來活力。在本節目中，您將聽到工程師和高層討論在汽車、工業與消費性電子等市場的電力電子相關新聞、挑戰和商機。歡迎我們的主持人，Power Electronics News和EEWeb.com主編Maurizio Di Paolo Emilio。
MAURIZIO DI PAOLO EMILIO: Hello everyone, and welcome to this new episode of PowerUP. Today we will talk about GaN devices for space applications with Bel Lazar, Chief Executive Officer of EPC Space. Unlike silicon, whereby specific manufacturing processes and packaging are required to insulate semiconductors from the effects of radiation, GaN devices are largely resistant to the issues caused by space radiation due to their physical characteristics and structure. GaN-powered devices should be the ideal choice for power conversion applications in space because they are more robust than hard-rad MOSFETs when exposed to various forms of radiation. Electrical and thermal performance of GaN has also demonstrated superior operation in a space environment. In this podcast with Bel Lazar, Chief Executive Officer of EPC Space, we will analyze the importance of GaN for space. Bel brings thirty and more years of experience in the semiconductor, aerospace, and defense technology fields. In addition to his role as a CEO of EPC Space, Bel currently serves as COO of Efficient Power Conversion, EPC. Let’s talk with Bel.
Hi Bel. Thanks a lot for being here. Thanks a lot for having you with PowerUP. How are you?
MAURIZIO DI PAOLO EMILIO：大家好，歡迎收聽最新一集的PowerUP。今天，我們將與EPC Space執行長Bel Lazar討論航太應用中的氮化鎵(GaN)元件。相較於矽元件由於需要特殊製造製程和封裝，才能隔離半導體免於輻射效應，GaN元件則由於其物理特性和結構，在很大程度上可以抵抗太空輻射引發的問題。GaN功率元件將會是實現航太功率轉換應用的理想選擇，因為它們在暴露於各種輻射形式時比抗輻射的MOSFET更堅固耐用。GaN的電和熱特性在太空環境中也展現出卓越的運作性能。在這集podcast中，EPC Space執行長Bel Lazar將分析GaN對於航太產業的重要性。Bel Lazar在半導體、航太和國防技術領域擁有30多年的經驗。除了擔任EPC Space的執行長，Bel目前也是Efficient Power Conversion (EPC)的營運長。讓我們和Bel好好地聊聊。
BEL LAZAR: Good, good. And you? Maurizio, thank you for this opportunity. Thank you very much.
MAURIZIO DI PAOLO EMILIO: Thank you. I’m fine. Good. So where are you located, Bel?
MAURIZIO DI PAOLO EMILIO：謝謝。我很好。好的，那麼，Bel，您現在在哪裡？
BEL LAZAR: I am located in Los Angeles, California, United States.
MAURIZIO DI PAOLO EMILIO: Nice place, wonderful.
MAURIZIO DI PAOLO EMILIO：好地方，太棒了！
BEL LAZAR: Yes.
MAURIZIO DI PAOLO EMILIO: So before starting, today we will talk about GaN for space. But before that, tell me, tell us, tell to our Power Electronics community more about you. Please introduce yourself.
MAURIZIO DI PAOLO EMILIO：在節目開始之前，我們今天將討論用於航太產業的GaN元件。但在此之前，請告訴我，告訴我們，告訴我們的Power Electronics社群更多關於您的事。請您介紹一下你自己。
BEL LAZAR: Sure. My name is Bel Lazar. I’m an electrical engineer and a computer engineer. And I’ve been fortunate to be involved with radiation-hardened power electronics from the late 80s at International Rectifier, or IR. IR introduced the world’s first radiation-hardened power MOSFET, which I was part of that team. And in IR, I started as an electrical engineer with the aerospace and defense business unit. And eventually, I led the group. I was there at IR for 22 years. Then I moved to Microsemi Corporation as Corporate Senior VP of Operations. And then I became CEO of API Tech, a NASDAQ-traded RF-based company for aerospace and defense market. Then I joined Alex Lidow at EPC Corp in 2016. And I have completed 19 M&A transactions throughout my career. With regards to the GaN journey, the fun and excitement has just begun.
BEL LAZAR：當然。我的名字是Bel Lazar。我是個電子工程師也是電腦工程師。1980年代後期，我有幸能夠在International Rectifier (IR)參與抗輻射電力電子產品的研究。IR曾經推出世界上第一個抗輻射功率MOSFET，我正是該團隊的一員。我一開始在IR的航太和國防業務部門擔任電子工程師，最後還帶領了這個部門。我在IR工作了22年，接著轉換到美高森美公司(Microsemi Corporation)，擔任企業資深營運副總裁。後來我還成為API Tech的執行長—API Tech是納斯達克(NASDAQ)的上市公司，專為航太和國防市場提供射頻(RF)技術。我後來在2016年加入了Alex Lidow帶領的EPC Corp.。在我的職業生涯中，還曾經完成了19筆併購(M&A)交易。至於我在GaN的旅程，樂趣和興奮才剛剛展開。
MAURIZIO DI PAOLO EMILIO: So, GaN-powered devices for space. So let’s start with the space environment. So why is the space so difficult for the electronics? What are the radiations and levels in play in the space?
MAURIZIO DI PAOLO EMILIO：那麼，GaN驅動的元件適用於太空。就讓我們從太空中的環境開始說起吧！為什麼這個環境對於電子產品來說如此困難？在太空中所能接受的輻射和強度是多少？
BEL LAZAR: Well, Maurizio, as you know, the electronics in space actually face a very harsh environment that includes radiation effects. And these electronics on a satellite must endure, during the life cycle of a satellite; as you know, there are no repairs in the satellite. Once it’s launched, it’s there forever until it dies. For semiconductors, there are several types of radiation in this space. When the device actually in the satellite, they experience some form of high-energy radiation bombardment. They all experience it. There are three types of radiation, gamma radiation, neutron radiation, and heavy ion bombardment. And an energetic particle that can cause damage to a semiconductor can cause damage in three primary ways. It can cause traps in a non-conducting layer, or it can cause physical damage to the crystal, also referred to as displacement damage. Or it can generate a cloud of electron-hole pairs that will cause the device to momentarily conduct and possibly burn out in the process. Now, the physical properties and construction of a GaN device compared to silicon gives GaN superior immunity to the damage caused by radiation in space. So, let’s take them one at a time. Let’s discuss the gamma radiation first. And the industry uses a term called TID, or total ionizing dosage as a metric. Well, let’s talk about the silicon. Silicon is susceptible to this form of radiation, while e-GaN FETs are not. And numerous tests have revealed that the e-GaN FETs can withstand up to 40, and maybe even more, 40 megarads of total ionizing dosage without any noticeable effect on functionality of the device. This is due to the fact that an e-GaN fet, the gate is separated from the underlying channel by aluminum gallium nitride layer. And this layer does not accumulate charge when subjected to gamma radiation. So from a TID standpoint, e-GaN fet is completely immune.
So now let’s move on to the second type of radiation effect, which is neutron bombardment. Here, the primary failure mechanism is displacement damage, where you have high-energy neutrons will scatter up atoms in the crystal lattice and leave behind lattice defects. Now the impact of neutrons on GaN crystal in the entire device structure is minimum because GaN is superior performance under neutron radiation, is again, has a much higher displacement threshold energy then compared with silicon. Now the third type of radiation effect, which is called single event effect, or SEE, silicon devices are susceptible to three types of SEE. One is called single event rupture. The second is single-event burnout, and the third is single-event upset. e-GaN devices do not have a gate oxide, which means they are not prone to single-event rupture. In addition, e-GaN devices do not have the ability to conduct large number of holes very efficiently, and so they’re not prone to single event upset. Now, they are prone to a certain extent to, they can experience a rising range source leakage current, which could cause a device to exceed its datasheet. Now EPC has developed a family of e-GaN FETs that are immune to single events under heavy bombardment, like an 85 let, which is a measure of energy deposited per unit length as an energetic particle travels through the material. So, there you have it. Those are the effects radiation effects that the electrons in space could experience.
BEL LAZAR：嗯，Maurizio，如你所知，太空中的電子產品實際上面臨著非常惡劣的環境，其中包括輻射效應。在衛星上的這些電子產品必須能持續用於衛星的整個生命週期；你也知道的，我們無法在衛星上進行維修。一旦它發射後，就會永遠存在直到壽命終結。至於半導體元件，在太空中會面對幾種不同的輻射類型。當元件實際用於衛星後，可能經歷某種形式的高能輻射轟擊。它們都會經歷這一過程。輻射的形式分為伽馬輻射、中子輻射和重離子轟擊三種。會對半導體造成損壞的高能粒子可能透過三種主要方式造成損壞：它會在非導電層中造成陷阱，或對晶體造成實體損壞，也稱為位移損壞。或者，它可能產生一團電子–電洞對，導致元件瞬間導電並可能在此過程中燒毀。現在，相較於矽，GaN元件的物理特性和構造使得GaN對於太空中輻射造成的損害具有更高的免疫力。所以，讓我們一個一個來談。就從伽馬輻射先討論吧！業界使用稱為TID或總電離劑量的術語作為度量標準。那麼來談一下矽吧。矽容易受到這種形式的輻射影響，而e-GaN FET則否。過大量測試顯示，e-GaN FET可以承受高達40Mrad或甚至更多的總電離劑量，而不至於對元件的功能造成任何明顯影響。這是由於e-GaN FET——閘極與其下通道被氮化鋁鎵層隔開之故，而且該分層在受到伽馬輻射時也不會積聚電荷。所以從TID的角度來看，e-GaN FET是完全免疫的。
那麼，現在讓我們繼續討論第二種輻射效應，即中子轟擊。在這方面，主要的失效機制是位移損傷，即高能中子會分散晶格中的原子並留下晶格缺陷。現在，中子對整個元件結構中的GaN晶體影響最小，因為GaN在中子輻射下具有優越的性能，而且比矽具有更高的位移閾值能量。現在輪到第三種輻射效應，稱為單粒子效應或SEE，矽元件易於受到三種SEE的影響：一種稱為單粒子柵穿，二是單粒子燒毁，三是單粒子翻轉。e-GaN元件沒有閘極氧化物，這意味著它們不易發生單粒子柵穿。此外，e-GaN元件並未具備非常有效傳導大量電洞的能力，因而也不易發生單粒子翻轉。現在，他們很容易在某種程度上經歷範圍上升的源極漏極電流，從而可能導致元件超出其數據手冊的規格限制。因此，EPC如今已開發出一系列e-GaN FET，即使是在重轟擊下也不受單粒子效應影響，例如85 let，這是高能粒子穿過材料時每單位長度沉積能量的量度。所以你現在知道了，這些都是太空中的電子可能經歷的輻射效應。
MAURIZIO DI PAOLO EMILIO: So, let’s focus on some application of power management for space technology. So, the biggest driver of cost is the weight in a satellite and in power system, but it is in general, weight is proportional to efficiency. So, the more efficient a system is, the smaller it is, and the less thermal management is required. What are the issues, the problems in terms of power supply for space, that the designers are going to solve? So, gallium nitride devices are used in high volume and have several years of light heritage in main applications for space. You mentioned some advantages about GaN for space. In particular, what questions do consumers have for you, and how can GaN improve to provide the finest products?
MAURIZIO DI PAOLO EMILIO：那麼，讓我們關注於太空技術的一些電源管理應用。成本的最大驅動因素在於衛星以及電力系統中的重量，但一般來說，重量與效率成正比。所以，系統越有效率，它的尺寸就越小，所需的熱管理就越少。那麼設計師要解決的太空供電問題是什麼？由於氮化鎵元件已被大量使用，而且在太空的主要應用已有多年的傳承。您提到關於GaN在太空方面的一些優勢。特別是，消費者在這方面有些什麼問題，未來又該如何改善GaN以提供最佳產品？
BEL LAZAR: Very good question, Maurizio. The key, and we’ll talk more about it throughout. But the key difference between an e-GaN fet and silicon fet is that their figure of merit, or FOM, which is defined as a product or multiplication of the on resistance and the input gate charges, QG. So let’s take an example. Let’s say for similarly rated hard rad devices, let’s say 100 volt, 30 amps. A typical rad hard MOSFET has a figure of merit of about 2.9, while an equivalent e-GaN fet in space, in our space portfolio, is about .17, in both same units. So the lower the figure of merit, the easier it is to drive the device for a given on-state resistance. Generally speaking, and e-GaN will typically have a figure of merit that are about five times or less than equivalent MOSFET. But then again, okay, you say, okay, well, what does that really mean to the end user? Well, as you know, it takes much less power to drive the gate of a GaN fet whose characteristics are otherwise equivalent to similar fet, which means, really means, that the gate drive requirements aren’t as demanding for GaN fet as they are for a silicon fet. So, I’m going to give you here an example. It might get a little bit into some formula and detail, but at the bottom line, as you will see, its GaN is much more efficient to drive. But let’s say the gate input capacitors, or CISS, where a MOSFET is 5600 pF, while it’s 850 pF for the e-GaN fet.
Now the power losses, which are the key driving factor in the satellite. We don’t want to lose; you want to minimize your power losses. The power loss here to drive these capacitors is, the power loss is P, which is equal to the CISS times the square of the voltage gate, gate of the voltage, times the switching frequency. Now the gate voltage required to fully enhance the MOSFET is 12 volt, while a GaN fet is 5 volt. If we assume a 1 megahertz switching frequency, the MOSFET gate-related power loss is about 800 million watts, while the gate drive-related losses in the GaN is 21 million. So this is significantly lower. So, the lower the power losses equate to greater efficiency. For the gate drive circuit, it means it can be physically smaller as well, which is an important criteria for space-based application. So in space, like other markets, we’re trying to address weight, efficiency, reliability. In all these categories, e-GaN excels and outperforms the hard rad silicon. So, there you have it.
BEL LAZAR：Maurizio，這是很好的問題，我們將在整個過程中更進一步討論。但是，e-GaN FET和矽FET之間的關鍵區別在於其品質因或稱FOM，定義為導通電阻和輸入閘極電荷QG的乘積或乘數。舉例來說，針對額定值相似的抗輻射元件，假設其為100V、30A。典型的抗輻射MOSFET之品質因數約為2.9，而在我們的太空產品組合中，太空等效e-GaN FET在兩個相同單元中約為0.17。因此，品質因數越低，要為特定導通電阻驅動元件就越容易。一般而言，e-GaN的品質因數通常約為等效MOSFET的五倍或更低。但話又說回來，好的，你說這對終端用戶真正意味著什麼？如您所知，驅動GaN FET閘極所需的功率要少得多，其特性是在其他方面與類似的FET相當，這意味著，實際上閘極驅動對於GaN FET的要求並不像它們對於矽FET那樣地嚴苛。所以，讓我舉個例子。它可能涉及一些公式和細節，但歸根結底，正如您將看到的，它的GaN驅動效率更高。但假設閘極輸入電容器或CISS，其中MOSFET為5600pF，而e-GaN FET為850pF。
MAURIZIO DI PAOLO EMILIO：您能否具體舉例說明GaN在太空中的應用？我可以想到的是CDC轉換器和馬達驅動器。也許在這兩種應用之間的情況更為關鍵；而且，除了電源管理，是否還有其他可以使用GaN的應用？
BEL LAZAR: Sure. You know, EPC Space is a joint venture between EPC Corp and VPT, and VPT is a DC converter company in Virginia. Let me use an example from our strategic partner, VPT. So we have a, VPT has a DC-DC converter that uses e-GaN FETs from EPC Space. Let’s use an example of a product that, it’s called SGRB 128S, which has a 100-volt input and an adjustable output from 12 volt to 28 volt. Output, power output up to 400 watts, which is a high-power converter, and efficiencies up to above 96 percent. And it’s probably one of the highest efficiency high power DC-DC converter on the market today for space. Now, without this e-GaN, this efficiency would not have been possible. So typically, an e-GaN fet would add about two to three percentage points in efficiency, which is huge for space and other applications. Now, you talk about what other applications beside DC-DC converters. We sell a lot of, a lot of application. Among them is the motor drives. And so EPC Space has shipped over 120,000 [rad hard e-Gan FETs in motor drive applications for satellites reaction wheels. Over 400 of these satellites are flying today in orbit, and a couple hundred more is to come. So, in addition to the power management, so we’ve got these motor drives, and in addition to the motor drives, e-GaN are used for LiDAR applications, space, and control systems, such as e-GaN based drivers for large and micro-pumps in satellites. Such pumps can be used in spacecraft propulsion, propane management, such as refueling and other in space fluid management, such as cooling. So those are the examples of applications.
BEL LAZAR：當然。你也知道的，EPC Space是EPC Corp和VPT的合資企業，而VPT是位於維州的一家DC轉換器公司。讓我舉一個來自我們策略合作夥伴VPT的例子。VPT有一款DC-DC轉換器，使用了來自EPC Space的e-GaN FET。讓我們以另一款名為SGRB 128S的產品為例，它具有100V輸入和12-28V的可調輸出。功率輸出可達400W，屬於大功率轉換器，其效率可達96%以上，可說是當今市場上用於太空時效率最高的大功率DC-DC轉換器之一。如今，如果沒有這種e-GaN，是不可能實現這種效率的。因此，e-GaN FET通常會提高大約2-3個百分點的效率，這對於太空和其他應用來說已經相當巨大了。現在，針對您所問的，除了DC-DC轉換器之外還有哪些其他應用。我們銷售了許多、許多的應用，其中包括馬達驅動器。因此，EPC Space已經出貨超過120,000個用於衛星反應輪馬達驅動應用的抗輻射e-GaN FET了。目前，這些衛星中有400多顆在軌道上飛行，未來還會有數百顆。因此，除了電源管理之外，我們還有馬達驅動器，而除了馬達驅動器，e-GaN還用於光達(LiDAR)應用、太空和控制系統，例如基於e-GaN的大型驅動器，以及衛星中的微型泵。這種泵可用於太空船推進、丙烷管理(例如加油)和其他太空流體管理(例如冷卻)。這些都是應用的例子。
MAURIZIO DI PAOLO EMILIO: So, like wide band gap semiconductors, so as you know, we also have silicon carbide. Can silicon carbide be used on the same level in the space? So, what are the considerations you’re taught here? So, if I’m correct, in space missions, the voltages involved are actually lower than most of the AC line voltages. And in this range, GaN should be, is much higher performing than silicon carbide, so should be the better choice.
MAURIZIO DI PAOLO EMILIO：那麼，就像寬能隙半導體一樣，正如你所知道的，我們也有碳化矽元件。碳化矽能否用於同樣高度的太空中？那麼，您在這裡學到的注意事項是什麼？那麼，如果我知道的沒錯的話，在太空任務中，所涉及的電壓實際上低於大多數的AC電壓。而在此範圍內，GaN應該比碳化矽的性能更高很多，所以應該會是更好的選擇。
BEL LAZAR: Yeah. I mean, look. Silicon carbide has its benefits as well. You know, silicon carbide in spacecrafts where you have a need for like a high voltage, let’s say, or a 600 volt, maybe a thousand volt, there are certain applications, and also requires very high temperature, like maybe like greater than 400 degrees Cs, or for satellites that actually travel closer to certain planets. So, in this case, silicon carbide can be an acceptable solution. With silicon carbide, you don’t have to rely on the thermal radiators to dissipate heat, as the silicon carbide can handle very high temperature. Now, having said that, silicon carbide devices do not operate efficiently at lower voltage due to their design construction when compared to an e-GaN. In addition, they’re not as robust as the e-GaN FETs under single-event effects. So, if you need voltages less than 600 volts and efficient power management, and excellent single event, then e-GaN is a clear winner, both from efficiency and from a radiation immunity standpoint.
BEL LAZAR：是的。我的意思是，碳化矽也有它的好處。你知道的，太空船中的碳化矽需要高電壓，比方說是600V，也可能是1000V，還有某些應用也需要非常高的溫度，例如大於400℃，或是實際運行更接近某些行星的衛星。因此，在這種情況下，碳化矽可能是一種可接受的解決方案。使用碳化矽，您就不必依賴熱輻射器來散熱，因為碳化矽可以承受非常高的溫度。話雖如此，相較於e-GaN，碳化矽元件由於其設計結構而無法在較低電壓下高效運行。此外，在單粒子效應下，它們也不如e-GaN FET般地堅固。因此，如果您需要低於600V的電壓和高效的電源管理，以及出色的單粒子效應，那麼無論是從效率還是從抗輻射性的角度來看，e-GaN顯然都是贏家。
MAURIZIO DI PAOLO EMILIO: Great, thank you. So, Bel, my last questions, reliability. So, in terms of reliability, the space environment will be more important, just because it’s difficult for electronics because you have to be sure about the function of the devices, considering the cost of each space missions. What are the main tests to guarantee the best performance, and what are the next challenges from your perspective, your company?
MAURIZIO DI PAOLO EMILIO：太好了，謝謝。那麼，Bel，我的最後一個問題是可靠性。就可靠性而言，太空環境將會更重要，正因為它對電子產品來說很困難，因為你必須確定元件的功能，考慮到每次太空任務的成本。確保最佳性能的主要測試是什麼？從您的立場來看，您的公司面臨的下一個挑戰又是什麼？
BEL LAZAR: Yeah, absolutely. So, EPC as a company, performs extensive reliability testing on all devices, and the reliability reports are on the web. You can reference then any time you want. In addition, for hard rad e-GaN FETs, EPC Space performs 100 percent screening on what we call QCI testing per milcurve 9500 space level requirements. And so, we meet all the requirements for a military standard screening. For the next challenge for us is to develop slightly higher voltages [rad hard GaN FETs], and monolithic rad-hard ICs. In addition, we have recently introduced a series of EPC 7 [rad hard] devices that will be qualified with the US-based defense logistics agency, or DLA, for QPL product offering, which will allow us, allow EPC Space, to sell standard [rad hard] products that will be accepted worldwide. At the same time, we are actually planning on getting European Space Agency qualification and approval for GaN in space. So that’s our next challenge.
BEL LAZAR：是的，一點也沒錯。因此，EPC對所有的元件進行了廣泛的可靠性測試，這些可靠性的報告就公開在網路上，您可以隨時參考。此外，對於抗輻射e-GaN FET，EPC Space依據milcurve 9500太空級要求，對我們所謂的QCI測試進行了100%篩選。因此，我們滿足軍用標準篩選的所有要求。至於我們面臨的下一個挑戰，則是開發更高電壓[抗輻射GaN FET]和單晶片抗輻射IC。此外，我們最近推出了一系列EPC 7 [抗輻射]元件，這些元件都符合美國國防部後勤局(DLA)的QPL產品供應資格，這也將使我們(EPC Space)銷售全世界都能接受的標準[抗輻射]產品。與此同時，我們實際上正計劃取得歐洲太空總署的認證以及核准在太空中使用的GaN產品。這就是我們的下一個挑戰。
MAURIZIO DI PAOLO EMILIO: Thank you, Bel. Thanks a lot for joining at PowerUP and see you next. Thank you.
MAURIZIO DI PAOLO EMILIO：謝謝，Bel。非常感謝您加入這集PowerUP，我們下次再會。謝謝。
BEL LAZAR: Thank you, Maurizio. Thank you very much.
MAURIZIO DI PAOLO EMILIO: That brings us to the end of this episode. Stay tuned with more news and technical aspects about power electronics. If you are listening to this on the podcast page at eetimes.com or powerelectronicsnews.com, links to articles on topics we have discussed are shown in this page. PowerUP is brought to you by AspenCore Media. The host is Maurizio Di Paolo Emilio. And the producer is James Ead. Thank you, everyone, for listening. See you next episode. Stay tuned.
MAURIZIO DI PAOLO EMILIO：今天的這一集已經來到尾聲了。敬請持續關注有關電力電子的更多新聞和技術。如果您正在eetimes.com或powerelectronicsnews.com的podcas頁面上收聽此內容，那麼，在此頁面還供了與我們討論過的主題相關文章鏈接。PowerUP由AspenCore Media提供給您。主持人是Maurizio Di Paolo Emilio。製作人是James Ead。謝謝大家的聆聽。下集見。敬請關注。
參考原文：GaN Devices for Space Applications