LDMOS

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LDMOS (laterally diffused metal oxide semiconductor[1]) transistors are used in microwave/RF power amplifiers. These transistors are fabricated via an epitaxial silicon layer on a more highly doped silicon substrate.

Silicon-based LDMOS FETs are widely used in RF power amplifiers for base-stations as the requirement is for high output power with a corresponding drain to source breakdown voltage usually above 60 volts.[2] Compared to other devices such as GaAs FETs they show a lower maximum power gain frequency.

Manufacturers of LDMOS devices and foundries offering LDMOS technologies include TSMC, GLOBALFOUNDRIES, Vanguard International Semiconductor Corporation, Infineon Technologies, RFMD, Freescale Semiconductor, NXP Semiconductors, SMIC, MK Semiconductors and Polyfet.

RF power amplifiers based on single LDMOS devices suffer from relatively poor efficiency when used in 3G and 4G (LTE) networks, due to the higher peak-to-average power of the modulation schemes and CDMA and OFDMA access techniques used in this communication systems. The efficiency of LDMOS power amplifiers can be boosted using typical efficiency enhancement techniques, for example Doherty topologies or Envelope Tracking.[3]

References[edit]

  1. ^ STMicroelectronics Application Note AN1226 - Understanding LDMOS device fundamentals
  2. ^ van Rijs, F. (2008). "Status and trends of silicon LDMOS base station PA technologies to go beyond 2.5 GHz applications". Radio and Wireless Symposium, 2008 IEEE. Orlando, FL. pp. 69–72. doi:10.1109/RWS.2008.4463430. 
  3. ^ Draxler, P; Lanfranco, S. ; Kimball, D. ; Hsia, C. ; Jeong, J. ; van de Sluis, J. ; Asbeck, P.M. (2006). "High Efficiency Envelope Tracking LDMOS Power Amplifier for W-CDMA". Microwave Symposium Digest, 2006. IEEE MTT-S International. San Francisco, CA. pp. 1534–1537. doi:10.1109/MWSYM.2006.249605. 

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