Wideband IMD3 suppression through negative baseband impedance synthesis
Wideband IMD3 suppression through negative baseband impedance synthesis
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DOI：
10.1049/mia2.12075
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发表时间：
2021-03
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通讯作者：
William Sear;T. Barton
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作者：
William Sear;T. Barton
摘要提出了一种基于基带频率合成负阻抗终端的功率放大器（PA）线性化方法。负基带终端先前已被证明可以抑制功率放大器中的互调失真（IMD）产品。在这里，这种效应是使用PA的漏极和栅极偏置路径之间的被动反馈网络合成的，因此在不增加系统复杂性的情况下抑制了IMD。该设计的目标是在PA的3 - dB压缩点（P3dB）抑制IMD3，从而实现线性压缩，从而提高器件利用率和效率。基于对1 ~ 200 MHz频率范围内反馈响应的仿真，设计了一种网络拓扑结构，提供了偏置结构和适当的传递函数来抑制IMD3，展示了第一个在宽基带频率范围内实现这种行为的实用结构。实现了两种不同的传递函数，并将其性能与标准基带终端的标称设计情况进行了比较。由于该方法的反馈特性，稳定性也得到了解决。带有反馈的2.14 GHz概念验证样机在10 - 150 MHz频距范围内显示出高达9.5 dB的双音IMD3抑制，而不会降低扩音器的连续波性能。
National Science Foundation, Grant/Award Number: 1846507 Abstract This article presents a power amplifier (PA) linearisation approach based on synthesising a negative impedance termination at the baseband frequency. Negative baseband termination has been previously shown to suppress intermodulation distortion (IMD) products in power amplifiers. Here, this effect is synthesised using a passive feedback network between the drain and gate bias paths of the PA, so that the IMD is suppressed without an increase in the system complexity. The design targets IMD3 suppression at the PA's 3‐dB compression point (P3dB), enabling linear operation into compression, therefore, resulting in improved device utilisation and efficiency. Based on simulation of the feedback response over a 1‐200 MHz frequency range, a network topology is designed that provides both the bias structure and the appropriate transfer function for IMD3 suppression, demonstrating the first reported practical structure to realize this behaviour over a wide range of baseband frequencies. Two different transfer functions are implemented and compared in performance to the nominal design case with standard baseband terminations. Due to the feedback nature of the approach, stability is also addressed. The 2.14‐GHz proof‐of‐ concept prototype with feedback exhibits up to 9.5 dB suppression of the two‐tone IMD3 over 10‐150 MHz tone spacing, without reducing the CW performance of the PA.