设计了一个改进型的CMOS宽带低噪声放大器(LNA),其带宽为1—5GHz,可用于蜂窝通信系统和无线局域网设备中。该LNA采用两级结构：第一级是信号转换电路,将输入的单信号转变为差分信号,通过将转换电路集成到LNA内部,减少了接收系统中的分立器件;第二级是放大电路,采用共源-共栅MOS管级联电路提供增益,实现信号放大和良好的输出匹配。该LNA采用TSMC 0.18μm工艺实现,用ADS软件进行仿真验证,结果显示本文提出的LNA设计整个带宽的增益为14dB,并且保持了较好的增益平坦性,增益幅度小于1dB,回波损耗S11、S22均小于-10dB,有着良好的输入/输出匹配,电路噪声系数小于2.3dB。
The design of an improved CMOS wideband Low Noise Amplifier (LNA) is presented. The bandwidth range is between 1 —5GHz, and the LNA is able to be used in the devices for cellular communication system and wireless local area network. The LNA comprises two stages. The first stage circuit is able to transform the signal received from the antenna or fitter into differential signals. It is able to reduce the number of discrete components of receiver system by integrating the conversion circuit into the LNA. The second stage contains common-source and common-gate MOS transistors. This stage provides an enough power gain and a good output matching for signals. The performance of power gain becomes better by adding a matching inductance between two transistors of second stage circuit. The improved CMOS LNA is designed and simulated with TSMC 0.18μm technology by using ADS software. Results illustrate that the noise figure of the LNA is below 2.3dB in the range of 1—5GHz, the gain for entire bandwidth is 14dB and the scattering parameters of S11 and S22 are all less than -10dB, having good input and output matches of the low noise amplifier.
