一款超低噪声前置放大器的设计  

Design of Ultra-Low Noise Preamplifier

作　　者：常莉[1] 沈博[1] 鲁永康[1] 张晓飞[1] 

机构地区：[1]中国地质大学地球物理与空间信息学院,武汉430074

出　　处：《电子器件》2008年第6期1854-1856,共3页Chinese Journal of Electron Devices

摘　　要：对于一款为低阻抗信号源设计用分立元件组成的前置放大器的低噪声设计要点作了较为详细的阐述,设计据级联放大器理论,重点是降低第一个晶体管的噪声系数,为此选择PNP型超β晶体管,并使之工作在低Uce,低Ic1的微功耗状态,并采取低噪声阻容元件等措施。据此制作了电路并对其进行了测试。结果表明其等效输入噪声电压为0.12 nV/Hz,可称其为超低噪声前置放大器,可广泛应用于诸如锁相放大器等对噪声特性要求很高的微弱信号测试仪器中。A design of low noise preamplifier using discrete components for the low-impedance signal sources is spe- cifically presented. According to series-wound amplifiers theory,the focus is to reduce the noise factor of the first transistor. The design makes the ultra-β PNP transistors work in the low Uce, low Icl micro-power state,and takes choice of low-noise measures such as resistive and capacitive components, and then the corresponding circuit is in- troduced. The test result indicates that the circuit＇s equivalent input noise voltage is 0. 12 nV/√Hz,which could be called ultra-low noise preamplifier. This circuit can be used in weak signal detection such as the locked-in amplifier, which needs high performance in noise characteristics.

关 键 词：级联放大器 分立元件 PNP型超β晶体管 超低噪声 前置放大器 

分 类 号：TN722.3[电子电信—电路与系统]