利用Floquet泄漏干涉突破集成环行器的非互易隔离极限
Beating the nonreciprocal isolation limit of integrated circulators by Floquet leakage interference
浏览论文内容
中文总结 AI 辅助
本研究通过Floquet泄漏干涉，在65-nm CMOS微波Floquet环行器中实现40dB隔离度，突破了集成环行器的非互易隔离极限，为高频集成芯片发展奠定基础。
中文摘要 AI 辅助
采用半导体开关的时间调制是实现无磁集成非互易器件的可行途径，这类器件可提供大调制深度与高速度，但芯片级器件受限于开关的关态电容，该电容会诱导输入波向隔离端口的有害泄漏，从而对非互易隔离度设置了上限，这类泄漏在很大程度上限制了高频非互易集成系统的发展。本研究通过利用泄漏间的Floquet干涉突破该极限：在时间Floquet开关谐振器环行器中，两个相干泄漏会到达隔离端口，分别是谐振器振铃频率下存储波的释放，以及载波频率下的直接输入泄漏。研究表明，可创造条件使这两种泄漏发生相消干涉，甚至完全抵消，即便使用非理想半导体开关也能实现完美隔离。实验在65-nm CMOS微波Floquet环行器中证实了泄漏干涉，达到了40dB的隔离度，比开关的固有隔离度高出20dB以上；还证实泄漏干涉具有固有快速动态，在单个调制周期内即可建立，使研究人员能在0.6ns内反转环行手性。研究结果为实现具有超高非互易隔离度的高频集成芯片铺平了道路。
英文摘要
Time-modulation using semiconductor switches is a promising route to magnetless integrated nonreciprocal devices, as they can offer large modulation depths and high speeds. Yet, chip-scale devices are capped by the finite off-state capacitance of the switches, which induces detrimental leakage of the input wave to the isolated port, imposing a ceiling on the nonreciprocal isolation. Such leakage has largely constrained the development of nonreciprocal integrated systems at high frequency. Here, we beat this limit by using Floquet interference between leakages. In a time-Floquet switched-resonator circulator, two coherent leakages reach the isolated port: the release of the stored wave at the resonator's ring-down frequency, and the direct input leakage at the carrier frequency. We show that it is possible to create conditions under which the two leakages destructively interfere, and even completely cancel, yielding perfect isolation despite operating with non-ideal semiconductor switches. We experimentally confirm leakage interference in a 65-nm CMOS microwave Floquet circulator, reaching 40-dB isolation, which is more than 20 dB higher than the natural switch isolation. We also demonstrate that leakage interference has inherently fast dynamics, establishing itself within a single modulation period, allowing us to reverse the circulation chirality in 0.6~ns. Our results pave the way toward high-frequency integrated chips with ultra-high nonreciprocal isolation.
