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Eliminate the Influence of SMPS Ripple Noise for WiFi Receiver with LMS Algorithms
ZHANG Yan,BU Gang,WANG Mingming
Electronic Science and Technology    2019, 32 (1): 11-15.   DOI: 10.16180/j.cnki.issn1007-7820.2019.01.003
Abstract   (413 HTML6 PDF(pc) (1610KB)(36)  

Aim

ing at the problem of ripple when the switching mode power supply was applied to the RF front-end analog circuit, a scheme of eliminating ripple in the digital baseband by using adaptive filtering was proposed. WiFi transceiver system based on IEEE802.11b wireless communication protocol was established by using simulink, and LMS adaptive filter was utilized in digital baseband to suppress the ripple. Simulation results showed that the signal quality could be significantly improved by the adaptive filter. When the ripple amplitude was within 150 mV, the received signal could meet the protocol requirements. Based on these results, an adaptive filter was designed, including both front end and layout. The power consumption analysis showed that the final adaptive filter consumed only 1.35 mW at 33 MHz clock frequency and 1.98 V supply voltage, validating the possibility of using switching mode power supplies for WIFI receivers to achieve significant power savings.


Figure 3. Diagram of WiFi receiver RF front end
Extracts from the Article
根据系统需要,选择结构简单的零中频接收机作为WiFi接收机射频前端。根据文献[9]搭建WiFi接收机射频前端框图,如图3所示,射频前端输出模拟基带信号之后,通过ADC即可得到数字基带信号。数字基带信号再经过升余弦匹配滤波、自动增益放大(Automatic Gain Control,AGC)、DQPSK(Differential Quadrature Phase Shift Keyin)解调及解扩频,最终与初始随机信号进行误码率(Bit Error Ratio,BER)比较。
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