【作者】 陈伟；

【导师】 黄启俊；

【作者基本信息】 武汉大学 ， 微电子学与固体电子学， 2017， 硕士

【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。更多还原

【Abstract】 With the continuous development of the modernization process,the demand for communication is getting higher which requires not only the communication speed is faster,but also the transmission distance is farther.Traditional wire transmission loss and its small capacity have been unable to meet the requirements of the Internet development.Optical fiber communication rises sharply with wide bandwidth,large capacity,long transmission distance and anti-jamming advantages.In recent years,fiber to the home(FTTH),the chip interconnection,LAN and optical network have entered people’s daily lives,greatly improving the quality of life.In optical fiber communication system,the preamplifier is the most important part of the front-end amplifier.This topic uses the 5 5nm CMOS technology to design the communication rate 2.5Gbps ultra high sensitivity preamplifier.This chip is used in the optical fiber transmission and its speed class in the international synchronous digital system is STM-16.As the front-end optical receiver preamplifier circuit,its performance determines the performance of optical receiver,which has a great influence on limiting amplifier and the recovery of clock circuit,so it is the most difficult circuit to design and the performance index is also relatively harsh.The performance index of the 2.5Gbps transimpedance amplifier designed in this paper is as follows.Its differential transimpedance gain is 40K,the equivalent input noise current is 96nA,the low cut-off frequency is 20KHz,the high cut-off frequency is 1.85GHz,the sensitivity is-30.2dBm,the input dynamic range is 30dB,the input saturation current is 2mA and the current power consumption is 36.2mA,The whole chip uses the 3.3V standard power supply voltage.The preamplifier adopts the design concept of sub module,mainly divided into the core amplifier and bias circuit.The core circuit mainly includes the input stage,the single ended to differential amplifier stage,the differential amplifier stage,the output buffer stage,the automatic gain control module,the input current monitor module,and the photodiode supply voltage module.The bias circuit mainly includes a bandgap circuit,a main power supply circuit and a current bias circuit.The input stage converts the input optical current into voltage output,used for signal processing.The single ended to differential amplification stage converts the single ended voltage generated by the input stage to the differential voltage output to facilitate the connection with the second stage.The differential amplifier stage mainly amplifies the voltage signal,and can drive the output buffer stage.The output buffer stage is mainly driven by a 50 ohm load at the back stage to provide a large output amplitude to avoid electromagnetic interference.The bandgap circuit mainly improves a temperature independent voltage and a current proportional to the temperature.The main power supply circuit converts the output voltage of the bandgap circuit into a voltage source which can be loaded.The current bias circuit mainly provides multiple current output.更多还原