This article reports the first implementation of 3-bit millimeter-wave switched true-time-delay (TTD) phase shifters based on phase-change material (PCM) germanium telluride (GeTe). Two TTD phase shifters are presented. The first phase shifter is designed using four monolithically integrated PCM single-pole triple-throw (SP3T) switches to route the signal through delay lines. The insertion loss variation between various states is minimized by integrating two fixed PCM GeTe elements maintained in the crystalline state, along with the optimized width of the delay lines. The PCM switching cells are latching type, thus, consume no static dc power. The SP3T switches are connected back-to-back in two stages to provide a 3-bit phase shift with 20° precision. The second phase shifter is designed using two back-to-back connected PCM single-pole eight-throw (SP8T) switches. Both phase shifters are designed to operate over an 8 GHz wide frequency band with a center frequency of 30 GHz. The devices are fabricated in-house using an eight-layer microfabrication process. The proposed devices are highly miniaturized with an overall device area of 0.42mm2 and 1.4mm2 for the first and second phase shifter, respectively. The first phase shifter exhibit a measured average loss of 4.3 dB with a variation of ±0.3 dB and a return loss better than 20 dB, while the second phase shifter demonstrates low average measured loss of 3.8 dB with only ±0.2 dB loss variation and returns loss better than 17 dB at 30 GHz. Both phase shifters provide 180° linear phase shift with lower than 18 ps delay in the worst case.

中文翻译：

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用于毫米波相控阵的基于损耗补偿的 PCM GeTe 锁存宽带 3 位开关真延时移相器

本文报告了基于相变材料 (PCM) 碲化锗 (GeTe) 的 3 位毫米波开关真延时 (TTD) 移相器的首次实现。介绍了两个 TTD 移相器。第一个移相器使用四个单片集成 PCM 单刀三掷 (SP3T) 开关设计，通过延迟线路由信号。通过集成两个保持在晶态的固定 PCM GeTe 元件以及延迟线的优化宽度，可以最大限度地减少各种状态之间的插入损耗变化。PCM 开关单元是锁存型的，因此不消耗静态直流电源。SP3T 开关在两级中背靠背连接，以提供 20° 精度的 3 位相移。第二个移相器使用两个背对背连接的 PCM 单刀八掷 (SP8T) 开关设计。两个移相器都设计用于在中心频率为 30 GHz 的 8 GHz 宽频带上运行。这些设备是使用八层微加工工艺在内部制造的。所提出的器件高度小型化，第一和第二移相器的总器件面积分别为 0.42mm2 和 1.4mm2。第一个移相器的测量平均损耗为 4.3 dB，变化为 ±0.3 dB，回波损耗优于 20 dB，而第二个移相器的平均测量损耗低，仅为 3.8 dB，损耗变化仅为 ±0.2 dB 和回波30 GHz 时的损耗优于 17 dB。在最坏情况下，两个移相器都提供 180° 线性相移，延迟低于 18 ps。