An Implementation Of A 433MHz Wireless Transceiver

As a new communication technology,Wireless Body Region Network(WBAN)is a frontier and hot research topic.With the development of wireless communication technology and semiconductor industry,the WBAN with short distance and low power consumption will play more and more important role in the fields of health care and consumer electronics.This article refers to the IEEE 802.15.6 protocol to design a wireless transceiver system that meets the WBAN standard and works in the MICS band for medical implant systems.Firstly,we introduced the standard of WBAN and the physical layer,including narrowband(NB),Ultra wide band(UWB),Human network communication(HBC)and other layers,analyzed the main frequency bands,and selected suitable bands for wireless body area network which can be used for medical implant system which uses MICS band.Then the principle of wireless communication is introduced,and the digital communication system and its communication channel are introduced in detail,which provides a theoretical basis for the design of wireless transceiver system.Based on the WBAN standard,this paper presents a transmitter and receiver index for medical implant system.Which requires the Transceiver Operating frequency band in 400MHz~450MHz while the bandwidth is up to 1MHz and the data transmission rate is in 50kbps~150kbps.Transmit distances of Common sensing nodes is at 2~5 meters,which support multi-channel transmission and bidirectional transmission.For the transmitter,the maximum transmitting power is less than 0dBm,the adjacent channel power ratio is-26 dB and the error vector mode(EVM)is-11~-20 dB.For the receiver,the receiving power range is-90dBm~-40 dBm,the receiver sensitivity is-84dBm~-95 dBm,the adjacent channel suppression ratio is 6~17dB,and the output signal to noise ratio(SNR)is greater than 12 dB.According to the target requirement and the actual application environment,this paper analyzed the structure and the advantages and disadvantages of the different transceivers,and determined the structures of the low intermediate frequency receiver and the Superheterodyne transmitter.Then designed three key modules,including power amplifier(PA),low noise amplifier(LNA)and mixer.The power amplifier chooses AB type power amplifier to ensure good linearity and good efficiency.The low noise amplifier chooses the inductance source negative feedback structure,to reduce the noiseand guarantee certain gain.The mixer chooses the dual balanced active structure,the advantage of this structure is the low power consumption,the big gain and the small port feed.For system-level design,this paper analyzed the advantages and disadvantages of different modulation and demodulation techniques,and selected two kinds of modulation and demodulation ways of FSK and OOK.The OOK modulation makes up the disadvantage of low data rate of the FSK,but restricts the transmission distance.We can select the right way according to the requirement.Then this paper introduced the module design of the system and the PCB design.In the design of PCB,we should consider both place and route.The RF module,digital module and analog module should be separated,and the digital line,power line should be away from the RF circuit.In this paper,we choose the GSMC 0.13 um process,and the simulation tool is Spectre.We completed the test in the MICS test room and the test results show that the output power of the transmitter is less than 0dBm and in OOK modulation,the data rate is up to 200 kbps.The transmission distance can reach 2~5 meters and support two-way transmission and multi-channel transmission.