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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 4. BER improvement chart of received signal by using adaptive filter
(a)BER chart before and after adaptive filtering (b)BER improvement chart
Extracts from the Article
图4为自适应滤波器滤除开关电源纹波的仿真结果折线图。如图4(a)所示,当纹波幅度开始大于50 mV并逐渐增大时,未经过自适应滤波的接收信号误码率迅速上升;而经过自适应滤波的接收信号直到纹波幅度大于150 mV才逐渐增大。对应的误码率改善折线图如图4(b)所示,当纹波幅度高于150 mV之后,本次仿真系统中未处理的高次谐波能量增加,导致误码率改善程度减小。由此可见,在针对实际应用选择合适的结构之后,自适应滤波法可对开关电源纹波进行有效的抑制。
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