TR2014-003

A 5-Level Efficient IFPWM Power Coding Approach Encoding LTE for Class-S Digital-RF Transmitter with Distortion Correction


    •  Zhu, Q.; Ma, R.; Duan, C.; Mukai, K.; Shinjo, S.; Teo, K.H., "A 5-Level Efficient IFPWM Power Coding Approach Encoding LTE for Class-S Digital-RF Transmitter with Distortion Correction", IEEE Radio Wireless Week (RWW), January 2014.
      BibTeX Download PDF
      • @inproceedings{Zhu2014jan,
      • author = {Zhu, Q. and Ma, R. and Duan, C. and Mukai, K. and Shinjo, S. and Teo, K.H.},
      • title = {A 5-Level Efficient IFPWM Power Coding Approach Encoding LTE for Class-S Digital-RF Transmitter with Distortion Correction},
      • booktitle = {IEEE Radio Wireless Week (RWW)},
      • year = 2014,
      • month = jan,
      • url = {http://www.merl.com/publications/TR2014-003}
      • }
  • MERL Contacts:
  • Research Areas:

    Electronics & Communications, Wireless Communications


TR Image
The generated switching pulse-train spectrum (3-/5-level).

In this work, for the first time we propose a multi-level intermediate frequency pulse width modulation (ML-IFPWM) power coding approach to generate a high speed pulse train as input of GHz class-S switch-mode PA in the digital-RF transmitter. The key feature of a high power coding efficiency of 68.5% from a 5-level digitally implemented discrete-time (DT)-PWM quantizer encoding 20-MHz LTE signal (PAR of 10.25-dB) is verified by simulation. Unlike the traditional RFPWM, this new power coding process taking place at IF frequency of 100 MHz, offers a higher over-sampling ratio thus resulting in an improved output spectrum purity. In addition, a look-up-table based linearization unit is introduced in the digital-RF transmitter architecture to specifically correct the distortion caused by the nonlinear transformation of power encoder. To the author's knowledge, this is the most efficient power coding approach in a digital implementation reported so far encoding 20-MHz LTE at 2 GHz with low EVM of 4.1%.