MODULATION DRIVER WIDEBAND POWER DEVELOPMENT PROJECT

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 在毫米波ESR研究中，B 0外部磁场的高水平调制在化学和生物学中的广泛问题上是期望的，其中线宽通常很大（100 G），因为信噪比（SNR）与调制幅度（mod amp）成比例，mod amp小于或接近线宽的1/5。 对于我们的170和240 GHz频谱仪桥的B 0的高电平调制，我们设计了一个非常宽带的功率放大器，它能够稳定地驱动失调谐振负载，表现出很大的电抗分量。传统的音频功率放大器有时被用作调制线圈驱动器，但不太适合此类服务。通常，它们在高于约50 KHz的区域中效率低且特性差，特别是在驱动高电容性或电感性阻抗时。相比之下，ACERT调制放大器设计克服了这些限制。它以恒流（CC）或恒压（CV）模式工作，可以在直流至150 KHz的频率下产生高达50瓦的输出功率。利用市售的高压混合运算放大器，这种宽带功率驱动器设计简单，低成本和鲁棒性，但也具有高线性度和稳定性。其输出部分包括用于异常输出条件的检测和信号通知的规定，例如由于，调制线圈网络的失调。CC模式下的操作可最大限度地减少由于调制线圈自加热而导致的检测到的频谱中的幅度漂移，并允许在需要固定的输入-场比时使用恒定的磁场产生系数进行直接调制。CV模式允许在其他实验室应用中使用放大器，例如CD-ESR的压电致动器驱动器。 在调制驱动放大器的原型和测试部分之后，我们在项目计划中的下一步是为整个放大器设计一个紧凑的封装，并在未来一年内为HF和可能的CD-ESR使用构建几个集成单元。

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. High-level modulation of the B0 external magnetic field is desirable in millimeter-wave ESR studies over a wide range of problems in chemistry and biology where the linewidths are often large (100G) given that the signal to noise ratio (SNR) is proportional to the modulation amplitude (mod amp) for mod amps less than or approaching 1/5 of the line width. For high-level modulation of B0 in our 170 and 240 GHz spectrometer bridges, we have designed an extremely wideband power amplifier which is capable of stably driving off-tuned resonant loads which exhibit a large reactive component. Conventional audio-frequency power amplifiers, which are sometimes pressed into service as modulation coil drivers, are not well-suited for this type of service. Generally, they are inefficient and poorly characterized in the region above approximately 50 KHz, especially when driving highly capacitive or inductive impedances. The ACERT modulation amplifier design, in contrast, overcomes those limitations. It operates in either constant-current (CC) or constant-voltage (CV) modes, and can produce up to 50 watts of output power at frequencies from d.c. to 150KHz. Utilizing a commercially-available h.v. hybrid operational amplifier, this wideband power driver design is simple, low-cost and robust, but also features high linearity and stability. Its output section includes provisions for detection and signaling of abnormal output conditions, such as clipping due to, e.g., mistuning of the modulation coil network. Operation in CC mode minimizes amplitude drift in the detected spectrum due to modulation coil self-heating and permits direct modulation with a constant magnetic field generation coefficient, when a fixed input-to-field ratio is required. CV mode permits use of the amplifier in other laboratory applications such as piezoelectric actuator driver for CD-ESR. Having prototyped and tested sections of the modulation driver amplifier, our next step in the project plan is to design a compact package for the complete amplifier and construct several integrated units for HF, and possible CD-ESR use, during the coming year.