Journal of Xidian University

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Asymmetric biasing linearization technique for the human body communication transmitter

LIU Yang;YANG Yintang;LI Di;SHI Zuochen   

  1. (School of Microelectronics, Xidian Univ., Xi'an 710071, China)
  • Received:2016-01-15 Online:2017-02-20 Published:2017-04-01

Abstract:

An asymmetric biasing technique for the buffer is presented. Second order distortion at the output of the buffer is cancelled, which can be used in the human body communication (HBC) transmitter to shape the output spectrum. Realized by active resistors, asymmetric biasing applied to the gate of MOS transistors adjusts the second order nonlinearity coefficient of transistors so that the second order intermodulation products at the output of the buffer are cancelled. Designed in 0.35μm CMOS process and under a supply voltage of 1.8V, an HBC transmitter is designed. Simulation results show that IIP2 of the single-ended output buffer is optimized to 84dBm and that the transmitter output spectrum at 1MHz is attenuated to -127dBr, which meets the -120dBr requirement of the IEEE 802.15.6 standard.

Key words: integrated circuits, linearity, second-order intermodulation, transmitter, IEEE 802.15.6