ULTRA-HIGH SPEED SWITCHES FOR GENERATION OF NANOSECOND MICROWAVE PULSES

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 在FT-ESR和DQC ESR中，我们使用宽度为几纳秒的微波脉冲。这种脉冲的产生需要使用非常快的微波开关。我们从多家供应商处购买了市场上最快的交换机。它们基于不同类型的快速pin二极管。我们发现，它们的开关速度限制在上升时间为1-1.5 ns，下降时间为1.5-3.5 ns。 此外，在较短的边缘上观察到抖动。我们需要更快、更稳定的开关，上升和下降时间均短于1 ns，视频瞬变可忽略不计。而且，使用pin二极管开关很难使两个短脉冲彼此接近。我们成功地测试了基于MMIC技术的开关，具有改进的性能特性，并在最佳条件下在1 ns内双向切换。这种开关需要一个非常快的驱动器，能够在不到1 ns的时间内产生6 V的电压摆幅和300 MHz的数据速率。这是一个挑战，但我们已经接近解决这个问题。为了最大限度地减少开关时间和减少抖动到一个微不足道的水平，开关需要与驱动器集成使用表面贴装技术和引线键合技术。 这一未决项目的进一步进展取决于是否有资金将基于MMICS FET开关的开关连接到芯片上。需要连接器化封装以使开关适合在整个6-18 GHz频率范围内的实际使用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In FT-ESR and DQC ESR we use microwave pulses with a width of a few nanoseconds. The generation of such pulses requires the use of very fast microwave switches. We purchased from several vendors the fastest switches available on the market. They are based on different types of fast pin-diodes. We found their switching speed is limited to 1-1.5 ns for the rise time and to a somewhat greater value of 1.5-3.5 ns fall times. Also, jitter is observed on the shorter edges. We need faster, more stable switching with both rise and fall times shorter than 1 ns and negligible video transients. Also, it is difficult to bring two short pulses close to each other using pin-diode switches. We successfully tested a switch based on MMIC technology, with improved performance characteristics, and switching in both directions in 1 ns at optimal conditions. This type of switch requires a very fast driver capable of generating voltage swings of 6 V in less than 1 ns and a 300 MHz data rate. This is challenging but we are close to a solution of this problem. In order to minimize the switching time and reduce the jitter to an insignificant level the switch needs to be integrated with the driver using surface-mount technology and wire-bonding techniques. Further progress on this pending project is contingent on the availability of funds needed to connectorize switches based on MMICS FET switches available in chip form. The connectorized package is required to make the switch suitable for practical use throughout the 6-18 GHz frequency range.