应用于ETC的发射机模拟前端电路设计
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摘要
基于不停车电子收费系统(Electronic toll collection,ETC)的应用,设计了一款调制深度与输出功率均可调的5.8GHz直接变频发射机。该发射链路由8bit数模转换器(DAC)、低通滤波器(LPF)、混频器(Mixer)以及功率放大器(PA)构成。模拟前端部分的DAC采用分段电流舵结构,结合了二进制编码和温度计编码的优势;并利用电阻阵列实现了16级不同的调制深度。LPF则采用一个二阶有源低通滤波器和一阶无源滤波器级联而成。文中还证明了DAC和LPF共模电平存在差异时直接级联不影响电路功能的问题。芯片实现工艺为TSMC0.18μm。测试结果显示5.79GHz信号功率范围为-7.1~2.4dBm,临道泄漏功率比在载波频率为5.79GHz和5.8GHz时皆为-47dBc。
Aiming at the application of electronic toll collection,a 5.8 GHz direct-conversion transmitter was designed with tunable modulation depth and output power.The transmitter consists of an 8 bit DAC,LPF,mixer,and PA.A segmented current steering DAC in the analog front end of the transmitter combines the advantage of binary coding and thermometer coding.Besides,the resister array is used to achieve 16 levels modulation depth in DAC.The LPF is realized by a second order active low-pass filter and a passive filter.It is also proved that the circuit function is not influenced no matter whether DAC and LPF are in different common-mode voltages.This chip was achieved in TSMC 0.18μm technology.The test result of the transmitter shows the power range of the 5.79 GHz signal is-7.1~2.4 dBm.The ACPRis-47 dBc when the carrier frequency is 5.79 GHz or 5.8 GHz.
Aiming at the application of electronic toll collection,a 5.8 GHz direct-conversion transmitter was designed with tunable modulation depth and output power.The transmitter consists of an 8 bit DAC,LPF,mixer,and PA.A segmented current steering DAC in the analog front end of the transmitter combines the advantage of binary coding and thermometer coding.Besides,the resister array is used to achieve 16 levels modulation depth in DAC.The LPF is realized by a second order active low-pass filter and a passive filter.It is also proved that the circuit function is not influenced no matter whether DAC and LPF are in different common-mode voltages.This chip was achieved in TSMC 0.18μm technology.The test result of the transmitter shows the power range of the 5.79 GHz signal is-7.1~2.4 dBm.The ACPRis-47 dBc when the carrier frequency is 5.79 GHz or 5.8 GHz.
引文
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[4]王帅,黄海生,李鑫,等.一种10bit 200MS/s分段式电流舵DAC设计[J].电子技术应用,2017(04):55-57,61.
[5]Deveugele J,Steyaert M S J.A 10-bit 250-MS/s binary-weighted current-steering DAC[J]。IEEE J Solidstage Circuits,2006,41(2):320-329.
[6]Choi C,Choi J,Kim M,et al,A low power 2.4-GHz CMOS direct-conversion transmitter for IEEE 802.15.4[C].Wireless Symposium(IWS),2014:1-4.
[7]华成英,童诗白.模拟电子技术基础[M],北京:高等教育出版社,2006.
[8]Du Dingkun,Li Yongming,Wang Zhihua,An activerc complex filter with mixed signal tuning system for low-IF receiver[C].IEEE Asia Pacific Conf on Circuits and Systems,2006:1031-1034.
[9]Chen R L,Chang S J,A 6-bit current-steering dac with compound current cells for both communication and rail-to-rail voltage-source applications[J].in IEEETransactions on Circuits and Systems II:Express Briefs,2012,59(11):746-750.