1.2--2.2 GHz宽带低噪声放大器研制

为检测微弱的射电信号,要求望远镜接收机噪声性能良好.低噪声放大器(Low Noise Amplifier, LNA)作为接收机前端关键电路,其噪声系数和增益决定了整机的噪声性能.设计了一款1.2–2.2 GHz的低噪声放大器,电路采用两级级联结构,第2级通过引入负反馈,在改善增益平坦度和拓宽带宽的同时减小噪声,级间经过后级输入阻抗优化后仅需一个隔直电容.并引入有损输出匹配网络,实现高增益、低噪声、良好回波损耗和较为平坦的宽带LNA设计.测试结果表明,在1.2–2.2 GHz频段增益30–33 dB,噪声温度平均值为47 K,输出1 d B压缩点大于11.3 dBm.测试性能良好,可用于该频段接收机系统中.

Development of 1.2--2.2GHz Wideband Low Noise Amplifier

In order to detect the weak radio signal, the telescope receiver requires good noise performance. As the key circuit of the receiver front end, the noise coefficient and gain of the low noise amplifier (LNA) determine the noise performance of the whole machine. A 1.2--2.2 GHz low noise amplifier is designed. The circuit adopts a two-stage cascade structure. The second stage introduces negative feedback to improve the gain flatness and broaden the bandwidth while reducing the noise. After the post-stage input impedance optimization, only one capacitor is needed between the stages. Lossy output matching network is introduced to realize high gain, low noise, good return loss and flat broadband LNA design. The test results show that the gain is 30--33 dB in the 1.2--2.2 GHz band, the average noise temperature is 47 K, and the output 1 dB compression point is greater than 11.3 dBm. Test results show that the device has good performance, which can be used in the receiver system in this frequency band.