人体信道发射机的非对称偏置线性化技术

Asymmetric biasing linearization technique for the human body communication transmitter

笔者设计了一个基于非对称偏置技术的缓冲器.该缓冲器输出端的偶次失真被消除,可应用于IEEE802.15.6人体信道发射机来进行输出频谱整形.非对称偏置技术利用有源电阻实现金属氧化物半导体栅极非对称偏置,调节晶体管二阶非线性系数,使缓冲器输出电流中二阶互调项被抵消.基于0.35μm金属氧化物半导体场效应晶体管工艺和1.8V电源电压设计了一个完整人体信道发射机.仿真结果显示,单端输出缓冲器的二阶输入截点可以优化到84dBm,人体信道发射机输出频谱在1MHz处被抑制达-127dBr,满足IEEE 802.15.6协议中-120dBr的要求.

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 0.35 μm CMOS process and under a supply voltage of 1.8 V, an HBC transmitter is designed. Simulation results show that IIP2 of the single-ended output buffer is optimized to 84 dBm and that the transmitter output spectrum at 1 MHz is attenuated to -127 dBr, which meets the -120 dBr requirement of the IEEE 802.15.6 standard.