高性能射频宽带放大器的设计与实现  

Design and implementation of high-performance RF wideband amplifier

作　　者：王贵锋[1] 

机构地区：[1]兰州理工大学技术工程学院,兰州730050

出　　处：《自动化与仪器仪表》2014年第11期131-134,共4页Automation & Instrumentation

摘　　要：以高性能VGA芯片AD8367和电流反馈运放OPA695为核心,设计并制作了带宽为0.3~100MHz,增益在0~60d B内连续可调的射频宽带放大器。该系统主要由前级固定增益放大器OPA695、两级压控增益放大器AD8367和末级电位器可调放大器OPA695四部分组成。在前级放大中,使用OPA695电流反馈型放大器实现输入RF信号的放大,前级输出的信号再经过由电压控制的AD8367使信号进一步实现放大。最后,经过OPA695的放大得到有效值大于1V的输出电压。系统通过阻抗匹配和磁珠级联耦合,使用BNC接头等措施减少噪声、避免自激。测试表明系统实现了高频微弱信号的精确不失真放大,且增益在0~60d B内连续可调。A wide-band radio freauency amplifier with bandwidth of 0.3-100MHz and contiuously adjustable gain from 0 to 60dB has been successfully designed fabricated using VGA chip AD8367 and current feedback operational amplifier OPA695 as the core. The system consists of the fixed-gain preamplifier OPA695, two stage voltage controlled gain amplifier AD8367 and the fi- nal potentiometer adjustable amplifier. The current feedback amplifier OPA695 was used to amplify the RF signal input in the fore-stage amplifier, whose output signal was further amplified by a voltage-controlled amplifier AD8367. Finally, the sigan was agan amplified by OPA695 to acquire the output voltage with the effective value high than 1V. The noise and self-excitation were ef- fectively elimilated from the ystems by using impedance matching, beads cascade coupling, BNC connectors and other methods. It is demonstarted by experimental test that the high frequency weak signal can be precisely amplified without any distortion.

关 键 词：可调增益 射频 宽带 阻抗匹配 VGA 

分 类 号：TN622.3[电子电信—电路与系统]