FAST PFN-BASED DRIVER FOR X-BAND RF CIRCULATOR SWITCH

这个子项目是许多研究子项目中的一个 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来源获得了主要资金， 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。 在升级我们的X/Ku微波EPR光谱仪的背景下，正在考虑改进高衰减射频（r.f.）切换接收器保护。如先前的子项目（SPID 0035）中所述，该子项目提出了一种拟议的循环器r.f.开关为35 GHz，我们已经开发出一种合适的手段，驱动铁氧体基环行器/隔离器波导r.f.在与我们的快脉冲光谱仪要求兼容的时间尺度上切换。实现这种快速射频的一个关键因素。开关子系统一直是一个固态高压驱动器的规格和设计，能够提供一个非常迅速，高价值的电流过渡通过开关？的电感铁氧体元件。 我们现在正在研究这种驱动器/开关技术在低频接收器保护中的应用。估计所需的能量切换的X/Ku环行器已作出，我们已经计算出的驱动器的电压和电流，必须达到。为了充分保护接收器，我们的X/Ku光谱仪应用要求驱动器应提供约250微焦耳的开关能量（而Q波段器件为87 uJ），以便可靠地切换环行器铁氧体磁化状态。这意味着大约25纳秒的矩形脉冲FWHM具有1500伏的顺应性和大约56安培的峰值。我们以前在模拟和评估高速开关驱动器参数方面的经验表明，离散脉冲形成网络（PFN）可能是指定的具有挑战性的驱动器性能条件的首选解决方案。在先前的设计分析中，我们注意到PFN的固有充电/放电对称性也可以被利用来提供所需的互补复位脉冲。 在可能的PFN拓扑结构中，结合我们可能采用的各种特性阻抗，根据我们以前的经验，我们将首先研究A型Guilleman形式的仿真，以确定最符合我们要求的源阻抗和负载阻抗。然后，我们将描述所需的环行器开关参数，并根据潜在供应商返回的设备规格，逐步建立更精确的模型。 根据这些信息，我们将对X/Ku接收器保护应用的高压开关参数进行最终设计改进。

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 the context of upgrading our X/Ku microwave EPR spectrometers, consideration is being given to improved high-attenuation radiofrequency (r.f.) switching for receiver protection. As described in a prior subproject (SPID 0035), which presents a proposed circulator r.f. switch for 35GHz, we have developed a suitable means of driving a ferrite-based circulator/isolator waveguide r.f. switch on a time scale compatible with our fast pulse spectrometer requirements. A crucial element in realization of this fast r.f. switch subsystem has been the specification and design of a solid-state high-voltage driver capable of delivering an extraordinarily rapid, high value current transition through the switch?s inductive ferrite element. We are now studying the application of this driver/switch technology to receiver protection at lower frequencies. An estimate of the energy required to switch the X/Ku circulator has been made, and we have calculated the driver voltages and currents which must be attained. In order to adequately protect the receiver, our X/Ku spectrometer application requires that the driver should provide around 250 microjoules of switching energy (as opposed to 87 uJ for the Q-band device), in order to reliably switch the circulator ferrite magnitization state. This implies a rectangular pulse FWHM of approximately 25 nsec with a compliance of 1500 volts and a peak value of approximately 56 amperes. Our previous experience in simulation and evaluation of driver parameters for high-speed switching has demonstrated that a discrete pulse-forming network (PFN) would likely be the preferred solution to the challenging driver performance conditions specified. In the prior design analysis, we noted that the PFN's inherent charge/discharge symmetry could also be exploited to provide the needed complementary reset pulse. Of the possible PFN topologies in combination with the various characteristic impedances which we might employ, based on our previous experience we will first investigate simulations of the Type A Guilleman form to determine the source and load impedances which best meet our requirements. We will then characterize the desired circulator switch parameters and progress to a more exacting model based on device specifications returned by prospective vendors. On the basis of this information, we will then conduct a final design refinement of the h.v. switch parameters for the X/Ku receiver protection application.