Design And Implement Of Multi-mode Broadband Low Noise Analog Front End Chip For Human Body Communication Receiver

Human Body Communication(HBC)is a novel short distance communication technology with the human body as transmission medium to transmit signal.Compared to traditional short distance communication technology such as Bluetooth,WiFi and RF,HBC is more secure both to human body and information,stronger in anti-jamming capability.Hence,HBC is recognized as one of the best information transmission schemes for Body Area Networks.There are two HBC transmission modes: capacitive coupling mode and galvanic coupling mode,which both have advantages,but the existing HBC systems can only achieve one mode of them,and can only accept current mode or voltage mode signal to input,it's not suitable for different human body electrodes or sensors which may have different signal output form.Which greatly limits the HBC system in compatibility and versatility.In this regard,a multi-mode wideband low noise Analog Front-End(AFE)chip for HBC receiver was designed in this paper,which has compatibility to capacitive coupling and current coupling HBC mode and can realize signal acquisition both to current and voltage.Proposed multi-mode wideband low noise HBC receiver AFE chip is mainly composed of a wideband low noise amplifier(LNA),current/voltage signal multiplexing amplifier and automatic gain control amplifier(AGC).According to the characteristics of HBC,an improved bandwidth expansion structure was introduced to the LNA,which makes the circuit bandwidth be increased,at the same time,without affecting the circuit gain and almost without introducing additional noise;A current/voltage signal multiplexing amplifier was proposed to adapt the diversity of HBC signal electrode and sensor,which simplifies the circuit design,at same time increase the circuit compatibility;An AGC amplifier was proposed to adapt the difference of body channel coupling degree for different electrode,attenuation characteristic for different body and signal transmission distance in different application,which makes the gain of the circuit can automatically adjust according to the output signal amplitude,thus the dynamic input range of the HBC receiver AFE is increased.Finally,0.18?m standard CMOS process was used to realized the principle design and layout design of the AFE circuit in this paper,and the layout simulation was done to verify the performance.The supply voltage is 1.8V,and the core layout area is 379.3 ?m�118.9 ?m.The simulation results show that,in the current input mode,the current equivalent input noise is 8.36pA/?Hz@50MHz,-3dB bandwidth is 0.26MHz~114MHz,and gain is 70.3dB?~ 112.5dB?;In the voltage input mode,the voltage equivalent input noise is 4.43nV/?Hz@50 MHz,-3dB bandwidth is 0.45MHz~112MHz,and gain is 41dB~83.2dB.The designed HBC receiver AFE meets the requirements of two kinds of HBC modes,and improves the compatibility and universality of the HBC system greatly.