一种双耦合双混频中频信号功率反馈电路

在自动电平控制系统中,常用功率反馈电路存在一个主要限制:调幅动态范围受限于电平检波器和相关电路,使其远远低于线性调制器的功率可变范围。文中介绍了一种双耦合双混频中频信号功率反馈电路,使检波器只需检测固定中频信号的功率大小即可反馈调节射频输出信号的功率幅度。经测试,电路射频输入信号在24 GHz变化时,得到的中频信号频率固定不变,等于晶振信号54 MHz。线性调制器的衰减量在031.5 dB变化时,中频信号功率与射频输出信号功率成良好的线性关系,满足预期的设计要求。

A Power Feedback Circuit of IF Signal With Dual-Coupled and Dual-Mixed

In ALC system, there is a major limitation of commonly used power feedback circuits: the amplitude modulation dynamic range is restricted by the level detector and associated circuitry, which is typically much lower than the power variable range of the linear modulator. This paper introduced a dual-coupled and dual-mixed IF signal power feedback circuit, so that the detector could feedback and adjust the power amplitude of the RF output signal only by detecting the power of the fixed IF signal. The test showed that when the RF input signal of the circuit changed at 24 GHz, the obtained IF signal was fixed, which was equal to 54 MHz of the crystal signal. And when the attenuation of the linear modulator changed from 0 to 31.5 dB, the IF signal power had a good linear relationship with the RF output signal power, which met the expected design requirements.