ULTRA-HIGH SPEED SWITCHES FOR GENERATION OF NANOSECOND MICROWAVE PULSES

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 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。我们从几家供应商那里购买了市场上最快的交换机。它们基于不同类型的快速管脚二极管。我们发现，它们的开关速度在上升时间限制在1-1.5 ns，在下降时间限制在1.5-3.5 ns的较大值。此外，在较短的边缘上观察到抖动。我们需要更快、更稳定的切换，上升和下降时间都小于1 ns，视频瞬变可以忽略不计。此外，使用PIN二极管开关也很难使两个短脉冲彼此靠近。我们成功地测试了一种基于MMIC技术的开关，性能特性得到了改善，在最佳条件下，双向开关只需1 ns。这种类型的开关需要一个速度非常快的驱动器，能够在不到1 ns的时间内产生6V的电压波动和300 MHz的数据速率。这是具有挑战性的，但我们接近解决这个问题。为了最大限度地减少开关时间，并将抖动降低到微不足道的水平，开关需要使用表面贴装技术和引线键合技术与驱动器集成。这一悬而未决的项目的进一步进展取决于连接基于芯片形式的MMICs FET开关的开关所需的资金的可用性。连接器封装是为了使开关适合在6-18 GHz的整个频率范围内实际使用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 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.