In this article, a wideband quasi-circulator (QC) with the low noise figure (NF) and high 1-dB compression point ( $\text{P}_{\text {1 dB}}$ ) is proposed. The slotline-based 180° hybrid is introduced to achieve the wideband high transmitter-receiver (TX-RX) isolation. Meanwhile, the bidirectional in-phase stage and the nonreciprocal out-of-phase stage are utilized to obtain specific power-split ratios for the low insertion loss and high antenna-transmitter (ANT-TX) isolation. By using the unequal power split, the proposed QC is without the fundamental 3-dB loss seen in reciprocal ANT interfaces. Besides, to further enhance the TX-RX isolation within a wideband, a reconfigurable inter-stage matching network based on a varactor-tuned capacitor is implemented. To verify the mechanisms mentioned above, a reconfigurable wideband QC operating at 1.75–2.9 GHz is implemented and fabricated. The total power consumption is 224 mW. The measurement exhibits in-band TX-RX isolation of 27–58 dB. The TX-ANT and ANT-RX insertion losses are 4.3–5.0 dB and 1.0–1.9 dB, respectively. The QC also achieves the minimum in-band ANT-RX NF of 3.4 dB. Meanwhile, the measured TX-ANT and ANT-RX IIP3s are 39.4 and 32.5 dBm, respectively. The TX input $\text{P}_{\text {1 dB}}$ is greater than 28.78 dBm, while the RX input $\text{P}_{\text {1 dB}}$ is 23 dBm. The TX-induced ANT-RX $\text{P}_{\text {1 dB}}$ is measured to be 28 dBm.

中文翻译：

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低NF和高P1dB宽带准循环器，具有不相等的功率分配和可重新配置的级间匹配

本文中的宽带准循环器（QC）具有低噪声系数（NF）和高1-dB压缩点（ $ \ text {P} _ {\ text {1 dB}} $ ）的提议。引入基于时隙线的180°混合信号以实现宽带高收发器（TX-RX）隔离。同时，双向同相级和不可逆异相级被用于获得特定的功率分流比，以实现低插入损耗和高天线发射器（ANT-TX）隔离。通过使用不均等的功率分配，所提出的QC不会在互惠的ANT接口中看到基本的3-dB损耗。此外，为了进一步增强宽带内的TX-RX隔离度，实现了基于变容二极管调谐电容器的可重构级间匹配网络。为了验证上述机制，实现并制造了工作于1.75–2.9 GHz的可重配置宽带QC。总功耗为224 mW。测量结果显示带内TX-RX隔离度为27-58 dB。TX-ANT和ANT-RX插入损耗分别为4.3–5.0 dB和1.0–1.9 dB。QC还实现了3.4 dB的最小带内ANT-RX NF。同时，测得的TX-ANT和ANT-RX IIP3分别为39.4 dBm和32.5 dBm。TX输入 $ \ text {P} _ {\ text {1 dB}} $ 大于28.78 dBm，而RX输入 $ \ text {P} _ {\ text {1 dB}} $ 是23 dBm。TX诱导的ANT-RX $ \ text {P} _ {\ text {1 dB}} $ 测得为28 dBm。