针对近地层自由空间紫外通信信号微弱的特点, 在阐述紫外信号调制方式的基础上, 提出了放大器的选频特性及其指标。围绕预定的指标要求设计了选频电路和三级放大电路, 通过增益调整电路进行增益的补偿和微调, 使总体特性曲线可以满足实际使用的需求。用 Multisim进行放大器仿真, 结果表明: 该放大器在 30 kHz和 50 kHz两个中心频率具有 10 000～100 000之间连续可调的放大倍数, 中心频率附近的带宽约 2 kHz,等效输入噪声电压5 nV/Hz @30 kHz、50 kHz。设计中采用了低噪声器件, 使放大器更适合用于近地层微弱紫外信号的放大, 这对实际工作有一定的参考意义。

According to the characteristics of the UV communication signals in free space near surface layer, based on the modulation methods of UV signals, the frequency-choosing characteristics and specifications of ampli. fiers are proposed. Based on the predetermined specifications, frequency-choosing circuits and three -level amplifi. cation circuits are designed. The overall characteristic curves can meet the requirements of actual application for gains modulation circuits, which can perform gain compensation and gain trimming. The simulation results by Multi. sim shows that: the amplifier has continuously adjustable gains magnification between 10 000～100 000 at the cen. ter frequency of 30 kHz and 50 kHz. And the bandwidth near center frequency is about 2 kHz, the equivalent input noise voltage is ≤ 5 nV/Hz @30 kHz、50 kHz. The amplifier is more suitable for magnifying weak UV signals near surface layer for using low-noise apparatus, which provides certain reference value for actual application.