潜用超高频通信中HDR模拟信号链路研究

摘要

针对传统的数字下变频(DDC)系统模拟前端增益动态范围低,响应速度慢,幅频特性平坦度差,噪声抑制效果差的模拟信号链路中信号调理的缺点,研究提出了一种应用于潜用超高频通信高速据率接收系统(high data rate receiver systems,HDR)中通用的55 dB高动态范围,快响应速度,噪声抑制效果好的模拟信号链路优化方案,并将其在终端HDR解调器系统的平台上实现.该方案采用陶瓷带通滤波器(band-pass filter,BPF)模块,数字式程控可变增益放大器(digital control variable gain amplifier,VGA),低噪声放大器(low noise amplifier,LNA),RF/IF固定增压放大单元和1.7 GHz高输入带宽的模数转化器(analog-to-digital converter,ADC)组成,实现了对720 MHz和1.2 GHz中频模拟信号采样,调理和自动增益控制(automatic gain control,AGC).实验结果表明,该方案能自动、快速实现增益控制,动态范围广,通带范围内各个增益点的幅频特性好,功耗低,噪声抑制效果良好.%Due to the low dynamic range of the analog front end, low respond speed, bad flatness of the Amplitude-fre-quency characteristics and the poor noise suppression capability of the signal conditioning in the analog signal chain of the traditional digital down converter (DDC)system, an improved analog signal chain scheme used in high data rate receiver (HDR)of the submarine UHF communication system has been put forward. This scheme has 55 dB dynamic range, highre-spond speed and good noise suppression capability. The scheme consists of a band-pass filter module, a digital controlvari-able gain amplifier (VGA), a low noise amplifier (LNA), a radio or intermediate frequency gain block and an ADC which has 1.7 GHz input bandwidth. It realizes sampling and conditioning of the 720 MHz and 1.2 GHz intermediate frequencysig-nal and automatic gain control (AGC). Experimental results show that the scheme has the characteristics: automatic and fast gain control, wide dynamic range and good amplitude-frequency characteristics of the gain points in the pass-band, low power consumption and good noise suppression capability.