基于肖特基二极管的反射式可调预失真电路

为解决传统反射式预失真电路可调性不高、对功率放大器的邻信道泄漏比(ACLR)改善量小的问题,文 中提出了一种基于肖特基二极管的反射式可调模拟预失真电路。该电路由90°电桥、肖特基二极管以及偏置电路组 成。每条支路采用两个并联肖特基二极管产生非线性信号,以抵消功放的非线性失真。每一个肖特基二极管都有独立 的偏置电路,从而可以增加电路调节的自由度。通过改变每个肖特基二极管的偏压,可实现更大动态范围的幅度和相 位的补偿。基于此原理加工的S 波段模拟预失真电路对中心频率为3. 5 GHz 的Doherty 功率放大器进行线性化测试, 实验结果证明:加上提出的模拟预失真电路后,在输出功率为-28 dBm 时被测功放的ACLR 改善了14. 6 dBc 以上。

Reflective Adjustable Predistortion Circuit Based on Schottky Diode

In order to solve the problem that the traditional reflective predistortion circuit has low adjustability and little improvement on the Adjacent Channel Leakage Ratio (ACLR) of the power amplifier, this paper proposes a reflective adjustable analog predistortion circuit based on Schottky diodes. The circuit consists of 90 ° bridge, Schottky diode and bias circuit. Each branch uses two parallel Schottky diodes to generate nonlinear signals to offset the nonlinear distortion of the power amplifier. Each Schottky diode is an independent bias circuit, which can increase the degree of freedom of circuit regulation. By changing the bias of each Schottky diode, the amplitude and phase compensation of a larger dynamic range can be achieved. The S-band analog predistortion circuit based on this principle is used to linearize the Doherty power amplifier with a center frequency of 3. 5 GHz. The experimental results show that the ACLR of the measured power amplifier is improved by more than 14. 6 dBc when the output power is -28 dBm.