手機射頻系統有三個(gè)主要零組件，收發(fā)器（Transceivers）、功率放大器（Power Amplifier，下簡(jiǎn)稱(chēng)PA）和天線(xiàn)開(kāi)關(guān)，有時(shí)PA包含在前端模塊（Front-End-Module，簡(jiǎn)稱(chēng)FEM）。2G時(shí)代的射頻系統只占大約1.5美元的成本，3G時(shí)代則占大約6-8美元的成本，4G時(shí)代則占大約8-10美元的成本，也是手機升級換代成本增加最多的部分。
收發(fā)器是手機平臺的一部分，通常提供手機基頻的廠(chǎng)家都要提供收發(fā)器，兩者基本上一一對應的關(guān)系。諾基亞是個(gè)例外，它采用德州儀器的基頻，但是卻采用意法半導體或英飛凌提供的收發(fā)器。不過(guò)現在意法半導體在合并了NXP和愛(ài)立信移動(dòng)平臺后推出基頻的能力大大增強。對那些躍躍欲試的小廠(chǎng)家來(lái)說(shuō)，收發(fā)器的行業(yè)門(mén)檻很高，因為小廠(chǎng)家通常只能提供單一的收發(fā)器而不能提供基頻。
PA是手機中最關(guān)鍵的元件，它決定了手機的通話(huà)質(zhì)量、通話(huà)時(shí)間、待機時(shí)間、信號強度。PA從一開(kāi)始就牢牢掌握在復合半導體廠(chǎng)家的手中，這些廠(chǎng)家最主要的產(chǎn)品就是PA。PA領(lǐng)域主要的廠(chǎng)家有RFMD，Skyworks，Triquint，Anadigics，Avago，Renesas（瑞薩）。瑞薩的PA全部繼承自日立半導體時(shí)代的產(chǎn)品，瑞薩成立后在PA領(lǐng)域毫無(wú)建樹(shù)，沒(méi)有推出過(guò)新產(chǎn)品，也沒(méi)有推出適合3G的PA。
RFMD一直是PA界的老大，不過(guò)Skyworks與RFMD的差距越來(lái)越小。RFMD過(guò)分依賴(lài)諾基亞和摩托羅拉，這兩個(gè)廠(chǎng)家對RFMD PA領(lǐng)域的銷(xiāo)售額貢獻度超過(guò)75%。RFMD過(guò)分依賴(lài)大客戶(hù)，缺乏議價(jià)能力，最近處于虧損中。實(shí)際諾基亞也過(guò)分依賴(lài)RFMD，90%以上的PA都來(lái)自RFMD。Skyworks主要客戶(hù)是索愛(ài)、LG、三星和摩托羅拉，客戶(hù)分散度高，風(fēng)險低。其技術(shù)實(shí)力也非常優(yōu)秀，全球第一片含有PA的4G FEM就來(lái)自Skyworks。
Triquint在技術(shù)和制造能力方面是最優(yōu)秀的，它同時(shí)也是全球最大GaAs代工廠(chǎng)。Triquint擅長(cháng)供應高集成度的PA，也擅長(cháng)PA的封裝，全球最小footprint的GSM PA，全球第一顆采用FC封裝的PA都是Triquint創(chuàng )造的，其主要客戶(hù)是三星、LG、RIM和蘋(píng)果。Anadigics和高通是親密合作伙伴，因此主要開(kāi)發(fā)CDMA和WCDMA領(lǐng)域的PA。在CDMA市場(chǎng)占有率比較高。Anadigics自成立以來(lái)一直在擴張，也導致其財務(wù)狀況不佳，近5年只有1年盈利。Avago脫胎自原惠普儀器及半導體部門(mén)的安捷倫。Avago領(lǐng)先其他廠(chǎng)家，最早開(kāi)發(fā)WCDMA領(lǐng)域，雖然前期銷(xiāo)售不佳，但是隨著(zhù)WCDMA的普及，其銷(xiāo)售額快速提升。
3G時(shí)代RF系統變得更加復雜，有些智能手機使用多達5個(gè)PA，一個(gè)針對所有的GSM頻帶，另外3個(gè)針對三個(gè)3G頻帶，還有一個(gè)是WLAN的PA。未來(lái)PA的發(fā)展趨勢肯定是集成度提高。Skyworks 和Triqunit在這方面最具潛力。4G時(shí)代對PA的要求更高，包括更線(xiàn)性的放大倍數，更高的峰谷比率，更高的效率。無(wú)論是2G還是3G時(shí)代，PA領(lǐng)域一直是復合半導體廠(chǎng)家的天下，傳統的硅半導體廠(chǎng)家根本無(wú)法染指。2G時(shí)代的PA通常是GaAs HBT，在3G時(shí)代，有些廠(chǎng)家繼續堅持GaAs HBT。有些廠(chǎng)家獨辟蹊徑，新進(jìn)廠(chǎng)家則多采用InGaP HBT，須要指出Skyworks已經(jīng)收購了飛思卡爾的PA部門(mén)。Skyworks在2009年推出了全球第一款針對LTE/EUTRAN的FEM，型號為SKY77445，其PADie采用InGaP BiFET工藝。Anadigics有兩款針對LTE/EUTRAN的PA，都采用了InGaP 。
6款典型3G時(shí)代PA對比
天線(xiàn)開(kāi)關(guān)也是一個(gè)高門(mén)檻領(lǐng)域，雖然其價(jià)格遠低于PA和收發(fā)器，通常要使用LTCC襯底和SiP封裝，全球主要由日本廠(chǎng)家供應，有村田、瑞薩和新日本無(wú)線(xiàn)。
Mobile phone RF system consists mainly of transceivers, power amplifier (abbreviated as PA thereafter) and antenna switch. PA might be set in the Front-End-Module or FEM. In 2G, the cost of RF system was only about US $1.5, while In 3G, the cost was increased to between US$6.0 and US$8.0, and the cost will further increased to about US$8.0 to US$10.0 in 4G, obviously, FR system had the highest cost growth during the upgrading of mobile phones.
The receiver is a part of the mobile phone platform. Generally the mobile phone baseband vendors also providing the receivers, however, Nokia’s baseband was from Texas Instruments, but its receiver was from ST Microelectronics or Infineon. ST Microelectronics has further enhanced its baseband ability through the consolidation between NXP and Ericsson mobile platform.
PA (Power Amplifier) is the most key component in a mobile phone, which decides the voice quality, connection time, standby time and signal strength. PA has been produced by compound semiconductor manufacturers all along, including RFMD, Skyworks, Triquint, Anadigics, Avago and Renesas. Renesas still relies on the previous products form Hitachi Semiconductor, launched none of any new products.
RFMD has always the NO.1, but the gap between RFMD and Skyworks is shrinking gradually. RFMD relies much on Nokia and Motorola. 75% sales of RFMD are contributed by those two. In the other hand, above 90% PA of Nokia is from RFMD. Skyworks’s main clients are Sony Ericsson, Motorola, LG and Samsung. The world’s first 4G FEM contains PA was from Skyworks.
As the world’s largest GaAs OEM, Triquint is good at high-integration PA, as well as the PA packaging. The GSM PA with the smallest footprint and the world’s first FC packaged PA were both produced by Triquint. The main clients of Triquint are Samsung, LG, RIM and Apple.
Anadigics has a close relationship with Qualcomm, which focus on the PA development for CDMA and WCDMA. Especially has a high market share in CDMA market. Since its establishment, Anadigics has been expanding continuously, but during the past five years, only one year is profitable.
Avago was previously the semiconductor department (Agilent) of HP. Avago was the first one engaged in the WCDMA development. Though its sales did not look good initially, with the increasing popularity of WCDMA, the sales turned to increase rapidly.
In 3G era, RF system becomes more complex. Some smart mobile phones have as many as five PAs, one is for all GSM frequency bands, one is for WLAN and the other three are for three 3G frequency band separately. Considering the high integration is the further development focus for PA, Skyworks and Triqunit have the biggest potential. 4G has much higher requirements to PA such as higher T/PR and higher efficiency. No matter in 2G or 3G, PA sector is always monopolized by compound semiconductor manufacturers; the traditional silicon semiconductors have no chances. PA was usually GaAs HBT in 2G , in 3G, new entrants tend to InGaP HBT, Skyworks had already acquired the PA department of Freescale. In 2009, Skyworks launched the world’s first model FEM (SKY77445) focus on LTE/EUTRAN. Anadigics also has two models of PA for LTE/EUTRAN, both of them adopted InGaP.
Six Typical PA Models in 3G
Antenna switch is also has high entry barriers. Although its price is rather lower than PA and receiver, usually requiring SiP packaing and LTCC underlay. Globally, antenna switches are mainly supplied by Japanese vendors such as MURATA, Renesas and New JRC etc.
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