Author
C. L. Ruthroff
Bio: C. L. Ruthroff is an academic researcher from Bell Labs. The author has contributed to research in topics: Balun & Impedance matching. The author has an hindex of 1, co-authored 1 publications receiving 308 citations.
Topics: Balun, Impedance matching, Transformer
Papers
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01 Aug 1959
TL;DR: Several transmission line transformers have been described which have bandwidth ratios as high as 20,000:1 in the frequency range of a few tens of kilocycles to over a thousand megacycles as discussed by the authors.
Abstract: Several transmission line transformers are described which have bandwidth ratios as high as 20,000:1 in the frequency range of a few tens of kilocycles to over a thousand megacycles. Experimental data are presented on both transformers and hybrid circuits. Typical applications are: interstage transformers for broad-band amplifiers; baluns for driving balanced antennas and broad-band oscilloscopes; and hybrids for use in pulse reflectometers, balanced modulators, etc. These transformers can be made quite small. Excellent transformers have been made using ferrite toroids having an outside diameter of 0.080 inch.
324 citations
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TL;DR: In this article, a new class of matching networks that greatly reduces the load sensitivity of resonant inverters and radio frequency (RF) power amplifiers is introduced, which serve to substantially decrease the variation in effective resistance seen by a tuned RF inverter as loading conditions change.
Abstract: A limitation of many high-frequency resonant inverter topologies is their high sensitivity to loading conditions. This paper introduces a new class of matching networks that greatly reduces the load sensitivity of resonant inverters and radio frequency (RF) power amplifiers. These networks, which we term resistance compression networks, serve to substantially decrease the variation in effective resistance seen by a tuned RF inverter as loading conditions change. We explore the operation, performance characteristics, and design of these networks, and present experimental results demonstrating their performance. Their combination with rectifiers to form RF-to-dc converters having narrow-range resistive input characteristics is also treated. The application of resistance compression in resonant power conversion is demonstrated in a dc-dc power converter operating at 100MHz
236 citations
TL;DR: Narrowband MPI is introduced, which dramatically reduces bandwidth requirements and increases the signal-to-noise ratio for a fixed specific absorption rate.
Abstract: The magnetic particle imaging (MPI) method directly images the magnetization of super-paramagnetic iron oxide (SPIO) nanoparticles, which are contrast agents commonly used in magnetic resonance imaging (MRI). MPI, as originally envisioned, requires a high-bandwidth receiver coil and preamplifier, which are difficult to optimally noise match. This paper introduces Narrowband MPI, which dramatically reduces bandwidth requirements and increases the signal-to-noise ratio for a fixed specific absorption rate. We employ a two-tone excitation (called intermodulation) that can be tailored for a high-Q, narrowband receiver coil. We then demonstrate a new MPI instrument capable of full 3-D tomographic imaging of SPIO particles by imaging acrylic and tissue phantoms.
125 citations
01 Jan 1968
TL;DR: In this paper, a comparison is made between photoconductive and photodiode detectors for heterodyne use in the infrared, and it is concluded that both are useful for communications applications.
Abstract: Heterodyne experiments have been performed in the middle infrared region of the electromagnetic spectrum using the CO 2 laser as a radiation source. Theoretically optimum operation has been achieved at kHz heterodyne frequencies using photoconductive Ge:Cu detectors operated at 4°K, and at kHz and MHz frequencies using Pb 1-x Sn x Se photovoltaic detectors at 77°K. In accordance with the theory, the minimum detectable power observed is a factor of 2/η greater than the theoretically perfect quantum counter, hvΔf. The coefficient 2/η varies from 5 to 25 for the detectors investigated in this study. A comparison is made between photoconductive and photodiode detectors for heterodyne use in the infrared, and it is concluded that both are useful. Heterodyne detection at 10.6 µm is expected to be useful for communications applications, infrared radar, and heterodyne spectroscopy. It has particular significance because of the high radiation power available from the CO 2 laser, and because of the 8 to 14 µm atmospheric window.
123 citations
99 citations
08 May 1990
TL;DR: In this article, a compact microstrip balun structure, capable of multioctave performance, has been devised for monolithic or hybrid circuit applications, which can be easily integrated with a variety of monolithic circuit designs such as mixers, multipliers, and class B push-pull amplifiers.
Abstract: A compact microstrip balun structure, capable of multioctave performance, has been devised for monolithic or hybrid circuit applications. The structure requires no suspended substrate techniques and can be designed to occupy only a small amount of circuit area, thus allowing it to be easily integrated with a variety of monolithic circuit designs such as mixers, multipliers, and class B push-pull amplifiers. If a matching network is incorporated with the balun structure, a 10:1 operational bandwidth can be achieved. >
92 citations