Name: iPhone 徹底改變了 RF 濾波器！ (The iPhone Forever Changed the RF Filter)
Uploaded: 2025-12-21T04:38:20.000Z
Duration: 22 min 22 s

The world is full of radio noise, random frequencies and waves.

世界上充滿了無線電雜訊、隨機的頻率和波。

情態副詞

As more devices go wireless, it only adds to the cacophony of noises.

隨著越來越多裝置無線化，這只會增加噪音的混亂。

So the big challenge for a mobile device is how to receive the right signals without interference.

所以，行動裝置面臨的一大挑戰是如何在沒有幹擾的情況下接收正確的訊號。

Just how amazing it is that your cell phone can receive the right signals from a far away tower out of sight.

你的手機竟然能接收到遠方看不見的基地臺的正確訊號，這真是太神奇了。

And the radio frequency, or RF filter inside your mobile's radio plays a critical role in pulling it off without a hitch.

而你手機裡的射頻，也就是 RF filter，在順利完成這件事上扮演著關鍵角色。

Prior to 2007, the RF filter industry was sleepy and did not attract much attention.

在 2007 年之前，RF filter 這個產業一直很沉寂，沒有引起太多關注。

Then Steve Jobs announced the iPhone and that forever changed the RF filter.

接著 Steve Jobs 發表了 iPhone，這永遠地改變了 RF filter。

In this video we talk about a subject perhaps a bit niche, but nevertheless vital.

在這支影片裡，我們要聊一個可能有點小眾，但卻非常重要的主題。

Basically put the radio filter does a simple job.

基本上，無線電濾波器的工作很簡單。

It is a circuit device that receives an input signal and creates an output based on that input signals frequency.

它是一種電路裝置，接收輸入訊號，並根據該輸入訊號的頻率產生輸出。

If the input frequency is within a certain desired frequency range, then that output needs to be similar to its original input, which is a pass, the pass band.

如果輸入頻率在某個期望的頻率範圍內，那麼輸出就應該與原始輸入相似，這就是通過，也就是通頻帶。

the output can't be identical due to a small impossible to avoid reduction, which we call insertion loss.

由於無法避免的微小損耗，輸出無法完全相同，我們稱之為插入損耗。

we do want it to be as low as possible because it means signal degradation.

我們希望它盡可能低，因為這意味著訊號衰減。

If the output is outside the desired range, then the output is zero.

如果輸出超出期望範圍，那麼輸出就是零。

Practically it can't be zero, but we want it to get as low as possible.

實際上不可能為零，但我們希望它盡可能低。

Chart this whole thing out and you get something that kind of looks like a woman's skirt or a Mesa.

把這個東西畫出來，看起來會有點像女生的裙子或是一個高原。

So in the industry, what they call a steep filter skirt means that the filter lets through a lot of the right bands and rejects the unwanted ones.

所以在業界，所謂陡峭的濾波器裙擺，意思就是這個濾波器能讓很多正確的頻段通過，同時拒絕掉不想要的訊號。

The industry uses a single dimensionless number to measure how good an RF filter is.

業界用一個無量綱的數字來衡量一個 RF filter 有多好。

就是帶通品質因數，也就是 Q。

There are other types of Q out there, but this is one for bandpass filters.

雖然還有其他類型的 Q，但這個是針對帶通濾波器的。

Q is defined as the ratio of the center frequency, in other words, the middle of the skirt to the low to high end of its frequency range.

Q 的定義是中心頻率，也就是裙擺的中間，除以它頻率範圍的低端到高端。

In other words, the width of the skirt or bandwidth.

換句話說，就是裙擺的寬度，也就是頻寬。

So center frequency divided by bandwidth.

The lower the insertion loss, the better.

When we talk about RF filters, we're referring to those with a frequency band between 100 MHz and 10 GHz.

當我們說到 RF filter 時，我們指的是頻帶介於 100 MHz 到 10 GHz 之間的濾波器。

Anything higher than that, we are probably talking about microwave filters.

高於這個範圍的，我們可能是在說微波濾波器。

So that is what the RF filter is supposed to do.

所以這就是 RF filter 應該要做的事。

There are many devices, but the RF filters inside our modern smartphones are SAW and BAW filters.

有很多裝置，但我們現代智慧型手機裡的 RF filter 是 SAW 和 BAW filters。

The concepts behind the SAW radio filter date back to the 1880s and Lord Reilla himself.

SAW radio filter 的概念可以追溯到 1880 年代，以及雷利勳爵本人。

In 1885, Rayleigh predicted and then created a mathematical formula for what we now call Rayleigh waves, A subtype of what we call surface acoustic waves or saw.

1885 年，Rayleigh 預測並創建了一個數學公式，用於我們現在稱為 Rayleigh waves，這是我們稱為 surface acoustic waves 或 SAW 的一個子類型。

These are waves traveling across the surface of a solid.

Seismic waves are another form of surface acoustic waves.

地震波是表面聲波的另一種形式。

And in fact that is the line of research the surface acoustic wave community took for the next 20 years or so.

事實上，這就是表面聲波社群在接下來的二十年左右所投入的研究方向。

Then came World War II, which greatly heightened the work done in the saw field.

接著第二次世界大戰爆發，這大大提升了在 SAW 領域的研究工作。

Radars work by sending out radio waves and reading what comes back.

雷達透過發送無線電波並讀取回傳的訊號來運作。

To get the best reading, we need a good radio filter to increase our signal to noise ratio.

為了獲得最佳的讀取結果，我們需要一個好的 RF filter 來提高我們的訊號雜訊比。

Then in 1965, a UC Berkeley professor, Richard White and his graduate student F.W.

然後在 1965 年，一位加州大學柏克萊分校的教授 Richard White 和他的研究所學生 F.W.

voltmer demonstrated an interesting effect with these surface waves using special comb shaped metallic electrodes called interdigitated transducers or idts.

voltmer 利用特殊的梳狀金屬電極，也就是 interdigitated transducers 或 idts，展示了這些表面波的一種有趣現象。

The phrase interdigitated refers to the electrodes arrangement with which resembles two interlocked hands.

interdigitated 這個詞指的是電極的排列方式，看起來就像兩隻交錯的手。

They then put two similar, if not structurally identical idts on top of a bar of crystalline quartz.

他們接著在一個石英晶體條的頂部放了兩個相似，如果不是結構相同的話，也是 idts。

The quartz bar acts as a piezoelectric substrate.

這個石英條扮演著壓電基板的角色。

Piezoelectric, referring to the conversion of electrical and mechanical energy.

壓電，指的是電能和機械能之間的轉換。

It has a critical role to play which will matter later.

它有一個關鍵的作用，這點之後會很重要。

When the first idt, an input idt, receives a radio signal that is within the desired frequency band, it will convert that radio signal into mechanical energy.

當第一個 idt，也就是輸入 idt，接收到一個在我們想要的頻帶內的無線電訊號時，它會將這個無線電訊號轉換成機械能。

That mechanical energy manifests as a unique surface acoustic wave traveling outwards from the IDT across the surface of the quartz bar.

這種機械能會以一種獨特的表面聲波形式表現出來，這種聲波會從 IDT 傳播到石英條的表面。

The wave then hits another IDT terminal, often called the output idt and it turns the wave into an electrical signal via the piezoelectric effect.

然後這個聲波會遇到另一個 IDT 端點，通常稱為輸出 idt，它會透過壓電效應將聲波轉換成電訊號。

This electrical signal can now enter the chipset to be interpreted.

這個電訊號現在可以進入晶片組進行解讀。

Some devices add what are called reflectors to both sides of the idt.

有些裝置會在 idt 的兩側加上稱為反射器的東西。

The waves will reflect back and forth between those reflectors trapped inside the filter.

聲波會在這些被困在濾波器內的反射器之間來回反射。

Like and spoilers for a 20 year old movie.

就像一部 20 年老電影的按讚和爆雷一樣。

That guy at the end of the first Saw movie.

第一部《奪魂鋸》電影結尾的那個傢伙。

Such devices are called surface acoustic wave resonators.

這樣的裝置就叫做表面聲波諧振器。

We should take some time to discuss how these systems are fabricated.

我們應該花點時間討論一下這些系統是如何製造的。

These are MEMS devices, RF MEMS to be precise.

這些是 MEMS 裝置，更精確地說是 RF MEMS。

MEMS stands for microelectromechanical devices and their design has tiny electro and mechanical devices whose production requires semiconductor technology.

MEMS 是微機電裝置的縮寫，它們的設計包含微小的機電裝置，其生產需要半導體技術。

The filter's effective frequency range is dependent on the distance of the gaps between the IDT electrodes, teeth or comb fingers.

濾波器的有效頻率範圍取決於 IDT 電極、齒或梳狀手指之間的間隙距離。

In the 1980s that gap was as small as 300nm.

在 1980 年代，那個間隙小到只有 300 奈米。

So we use deposition to deposit a thin film layer of metal, usually some aluminium alloy, on top of a piezoelectric substrate.

所以我們使用沉積法，在壓電基板上沉積一層薄金屬膜，通常是某種鋁合金。

That substrate is usually the aforementioned quartz crystal or lithium niobate.

這個基板通常就是前面提到的石英晶體或鈮酸鋰。

After that, we use lithography to pattern the filter's features onto that metal layer.

之後，我們用微影技術在金屬層上製作濾波器的特徵。

Usually that includes the IDT resonators and all that.

Having all the action take place on the filter surface makes the saw filter easier to manufacture.

所有的動作都在濾波器表面進行，這讓 SAW 濾波器更容易製造。

With early saw filters, you only needed to deposit, pattern and etch one layer.

早期的 SAW 濾波器，你只需要沉積、製作圖案和蝕刻一層。

More advanced saw filters might get more complicated, but on the whole, don't add that many more layers.

更先進的 SAW 濾波器可能會更複雜，但總體來說，不會增加太多層。

One manufacturing downside though, is that it does mean we need to be a bit more careful with regards to packaging.

不過，製造上的一個缺點是，我們需要對封裝稍微更小心一點。

We often sealed these into vacuums, which was challenging.

我們常常將它們密封在真空裡，這很有挑戰性。

After publication, Professor White and Voltmer apparently moved on from their work, unaware of its applications, which were apparently limited at the time.

發表之後，White 和 Voltmer 教授似乎就沒有繼續他們的研究了，他們不知道這項技術的應用，而且當時的應用似乎也很有限。

But later, the saw filter caught the industry's interest because it was a good small analog filter that worked on frequencies from 10 MHz to 1 GHz and beyond.

但後來，SAW 濾波器因為是一個很棒的小型類比濾波器，能在 10 MHz 到 1 GHz 甚至更高的頻率上運作，引起了業界的興趣。

The military were some of the first people to research these, trying to improve their communications systems.

軍方是早期研究這些技術的其中一群人，他們試圖改善他們的通訊系統。

In situations where interference can be accidentally or not accidentally be injected into the airwaves, good signal to noise ratios are critical.

在訊號可能被意外或非意外地注入空氣波的場合，良好的訊號雜訊比至關重要。

An SAW filter was used on the Voyager missions in the late 1970s.

SAW 濾波器在 1970 年代末的 Voyager 任務中使用過。

Tested for extreme environmental conditions.

在極端的環境條件下進行測試。

The filter has worked for nearly 50 years, though Voyager seems to be going through some recent issues.

這個濾波器已經運作了將近 50 年，雖然 Voyager 最近似乎遇到了一些問題。

Then in 1975, TV companies like Philips, Plessy and Siemens found that saw filters were good low cost replacements for the old coil and capacitor based filters in their TV sets.

然後在 1975 年，像 Philips、Plessy 和 Siemens 這樣的電視公司發現，SAW 濾波器可以低成本地取代他們電視機裡舊的線圈和電容濾波器。

Better filters meant being able to tune in to more TV channels without static interference.

更好的濾波器意味著能夠調諧更多電視頻道，而不會有靜態幹擾。

Something that used to be a problem back before Netflix and YouTube and all that.

以前，這曾經是個問題，在 Netflix 和 YouTube 出現之前。

Quickly after approving the use case, these TV companies started making 30 to 40 million of these units.

在核準使用案例後不久，這些電視公司就開始大量生產，一年有三千萬到四千萬個。

It was one of the first big RF MEMS products.

Motorola demonstrated the first wireless mobile phone in 1973, the DynaTAC.

Motorola 在 1973 年展示了第一支無線手機 DynaTAC。

The Dynatac used ceramic filters for their RF filtering needs.

DynaTAC 使用陶瓷濾波器來滿足他們的 RF filtering 需求。

And while those ceramics were smaller than the aforementioned coil and capacitor filters, they still took up a large portion of the system.

雖然這些陶瓷濾波器比前面提到的線圈和電容濾波器小，但它們仍然佔據了系統的很大一部分。

So as standards for 2G cellular communication systems developed throughout the 1980s, they looked for something smaller.

所以，隨著 1980 年代 2G 行動通訊系統標準的發展，他們開始尋找更小的東西。

Then in 1992, Fujitsu fabricated the first SAW resonator based RF filters for mobiles.

然後在 1992 年，富士通製造了第一款用於手機的 SAW resonator based RF filters。

它們體積小、便宜又容易製造。

字幕列表影片播放

iPhone 徹底改變了 RF 濾波器！ (The iPhone Forever Changed the RF Filter)

critical

material

demonstrate

pattern