2.5 Gbps高灵敏度光接收机前置放大器设计

发布时间：2018-06-29 02:58

本文选题：光纤通信 + 光接收机　；参考：《武汉大学》2017年硕士论文

【摘要】：现代化进程的不断发展,人们对通讯的要求越来越高,不但要求通信速率越来越快,传输的距离也越来越远,通信容量也越来越大。传统的电线传输损耗大且容量较小,已经不能满足互联网时代的要求。光纤通信以通信带宽宽,传输容量大,传输距离远和抗外界干扰性强等优势迅速崛起。近年来,光纤到户,芯片内互联,局域网,光网络等已经走入人们的日常生活,大大改善了生活质量。在光纤通信系统中,前置放大器是光接收机前端放大电路中最为重要的组成部分。本课题采用的是55nm_CMOS工艺,设计通信速率为2.5Gbps的高灵敏度的前置放大器,这个芯片用于光纤传输中国际同步数字体系的STM-16速率级。前置放大器作为光接收机第一级信号处理电路,其性能决定了整个光接收机的性能,对后级的限幅放大器和时钟恢复电路有很大的影响,因此也是最难设计的电路,其性能指标也是比较苛刻的。本课题设计的2.5Gbps跨阻放大器其差分跨阻增益为40kΩ,等效输入积分噪声电流为96nA,低频截止频率为20KHz,高频截止频率为1.85GHz,灵敏度为-30.2dBm,动态输入范围为30dB,输入饱和光电流为2mA,电源功耗电流为36.2mA,整个芯片采用3.3V标准电源电压供电。整个前置放大器采用分模块的设计理念,主要分为核心放大电路和偏置电路。核心电路主要包括输入级,单端转差分放大级,差分放大级,输出缓冲级,自动增益控制模块,输入电流监控模块,光电二极管供电电压模块。偏置电路主要包括带隙电路,主放供电电路和电流偏置电路。其中输入级是将输入的光电流转换成电压,供给后级信号的处理;单端转差分放大级是将输入级产生的单端电压转换成差分电压输出,以方便和后级连接;差分放大级主要将电压信号进一步放大处理,并且可以驱动输出缓冲级;输出缓冲级主要是驱动后级的50欧姆负载,要提供大的输出幅度,以避免电磁干扰;带隙电路主要提高一个与温度无关的电压和一个与温度成正比的电流;主放供电电路主要是将带隙电路的输出电压转换成能够带负载的电压源;电流偏置电路主要提供多路的电流输出。
[Abstract]:With the continuous development of modernization, people are demanding more and more communication, not only the speed of communication is getting faster and faster, the distance of transmission is also more and more distant, and the capacity of communication is becoming larger and larger. Traditional wire transmission loss and capacity is small, can not meet the requirements of the Internet era. With the advantages of wide communication bandwidth, large transmission capacity, long transmission distance and strong resistance to external interference, optical fiber communication has emerged rapidly. In recent years, fiber to home, chip interconnection, local area network, optical network and so on have entered people's daily life, greatly improved the quality of life. In optical fiber communication system, preamplifier is the most important part in the front end amplifier circuit of optical receiver. In this paper, 55 nm CMOS technology is used to design a high sensitivity preamplifier with a communication rate of 2.5 Gbps. This chip is used in STM-16 rate level of international synchronous digital system in optical fiber transmission. As the first stage signal processing circuit of optical receiver, preamplifier determines the performance of the whole optical receiver, and has a great influence on the limiting amplifier and clock recovery circuit, so it is also the most difficult circuit to design. Its performance index is also quite harsh. The 2.5Gbps transresistance amplifier designed in this paper has a differential transresistance gain of 40k 惟, an equivalent input integral noise current of 96nA, a low frequency cut-off frequency of 20kHz, a high frequency cut-off frequency of 1.85 GHz, a sensitivity of -30.2 dBm, a dynamic input range of 30 dB and an input saturation photocurrent of 30 dB. 2 Ma, the power consumption current is 36.2 Ma, the whole chip is supplied by 3.3V standard power supply voltage. The preamplifier is divided into core amplifier circuit and bias circuit. The core circuit mainly includes input stage, single-end differential amplifier stage, output buffer stage, automatic gain control module, input current monitoring module, photodiode power supply voltage module. The bias circuit mainly includes bandgap circuit, main amplifier supply circuit and current bias circuit. The input stage converts the input photocurrent into the voltage and supplies the post-stage signal processing; the single-end conversion differential amplifier stage converts the input stage's single terminal voltage into the differential voltage output to facilitate the connection with the rear stage; The differential amplifier stage mainly amplifies the voltage signal and can drive the output buffer stage, which mainly drives the 50 ohms load of the latter stage, and provides a large output amplitude to avoid electromagnetic interference. The band-gap circuit mainly increases a temperature-independent voltage and a current proportional to temperature, and the main amplifier circuit converts the output voltage of the band-gap circuit into a voltage source capable of load. Current bias circuit mainly provides multiple current output.
【学位授予单位】：武汉大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN722.71;TN929.11

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