低电压低功耗音频Σ-ΔADC调制器设计.docx

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低电压低功耗音频Σ-ΔADC调制器设计

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张涛何鹏刘劲

摘?要：针对应用于音频设备中的Σ-ΔADC，提出一款改进的Σ-ΔADC调制器.该调制器结构改进传统调制器的结构并对调制器系数进行优化，克服传统Σ-ΔADC调制器结构的缺点，同时对调制器中的两个关键电路即OTA放大器和比较器也进行优化，极大改善了OTA放大器和比较器性能.改进后的调制器具有低电压、低功耗、高精度和较好的鲁棒性的特点.该调制器采用1.2V低电压供电，过采样比（OSR）为128，采样频率为6.144MHz，信号带宽为20kHz.基于SMIC0.11μm的工艺下，完成了Σ-ΔADC调制器的版图设计，并最终流片成功.芯片流片后的成测结果表明，调制器的信噪比达到102.4dB，有效位达到16.7bit，调制器的整体功耗仅1.17mW左右，整个调制器的版图的面积仅为0.122mm2左右.调制器的成测性能指标表明，该调制器是音频芯片中Σ-ΔADC电路的良好选择.

关键词：模数转换器;Σ-Δ调制器;低功耗;低电压

中图分类号：TN432??????????????文献标志码：A

DesignofLowVoltageLowPowerAudioΣ-ΔADCModulator

ZHANGTao，HEPeng，LIUJing

（SchoolofInformationScienceandEngineering，WuhanUniversityofScienceandTechnology，Wuhan400080，China）

Abstract：AΣ-ΔADCmodulatorwithlowvoltageandlowpowerconsumptionisproposedfortheapplicationofΣ-ΔADCinaudioequipment.Themodulatorstructureimprovesthetraditionalmodulatorstructureandoptimizesthemodulatorcoefficients，thusovercomingtheshortcomingsofthetraditionalΣ-ΔADCmodulatorstructure.Atthesametime，OTAamplifierandcomparator，twokeycircuitsinthemodulator，areoptimized，whichgreatlyimprovestheperformanceofOTAamplifierandcomparator.Theimprovedmodulatorhasthecharacteristicsoflowvoltage，lowpowerconsumption，highprecisionandgoodrobustness.Themodulatorispoweredbya1.2Vlowvoltage，andithasanover-samplingratio（OSR）of128，asamplingfrequencyof6.144MHz，andasignalbandwidthof20kHz.BasedonSMIC0.11μmprocess，thelayoutdesignofΣ-ΔADCmodulatorwascompleted，andthestreamingchipwasfinallysuccessful.Themeasurementresultsafterchipstreamingshowthatthesignal-to-noiseratioofthemodulatorreaches102.4dB，theeffectivebitreaches16.7bit，theoverallpowerconsumptionofthemodulatorisonlyabout1.17mW，andthewholelayoutareaofthemodulatorisonlyabout0.122mm2.ThemeasuredperformanceofthemodulatorshowsthatitisagoodchoiceforΣ-ΔADCcircuit