Topic
LC circuit
About: LC circuit is a(n) research topic. Over the lifetime, 9471 publication(s) have been published within this topic receiving 109393 citation(s).
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Abstract: An array of single nonmagnetic metallic split rings can be used to implement a magnetic resonance, which arises from an inductor-capacitor circuit (LC) resonance, at 100-terahertz frequency. The excitation of the LC resonance in the normal-incidence geometry used in our experiments occurs through the coupling of the electric field of the incident light to the capacitance. The measured optical spectra of the nanofabricated gold structures come very close to the theoretical expectations. Additional numerical simulations show that our structures exhibit a frequency range with negative permeability for a beam configuration in which the magnetic field couples to the LC resonance. Together with an electric response that has negative permittivity, this can lead to materials with a negative index of refraction.
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Fig. 1. Illustration of the analogy between a conventional LC circuit (A), consisting of an inductance L, a capacitance C, and the single SRRs used here (B). l, length; w, width; d, gap width; t, thickness. (C) An electron micrograph of a typical SRR fabricated by electron-beam lithography. The thickness of the gold film is t 0 20 nm. For normal incidence, where the magnetic field vector B lies in the plane of the coil, the electric field vector E of the incident light must have a component parallel to the electric field of the capacitor to couple to the LC circuit. This allows the coupling to be controlled through the polarization of the incident light (Fig. 2). 
Fig. 2. Measured transmission (red) and reflection (blue) spectra. In each row of this ‘‘matrix,’’ an electron micrograph of the sample is shown on the right-hand side. The two polarization configurations are shown on top of the two columns. In the first row (A and B), the lattice constant of the SRRs is a 0 450 nm; in the second row (C and D), it is a 0 600 nm; and in the third row (E and F), it is a 0 900 nm. (A) to (F) correspond to nominally identical SRRs. In the last row (G and H), results for closed-ring resonators with a 0 600 nm are shown. The combination of these spectra unambiguously shows that the resonance at about 3-mm wavelength (highlighted by the gray areas) is the LC resonance of the individual SSRs. 
Fig. 3. (A to H) Calculated transmission (red) and reflection (blue) spectra, corresponding to the experiments shown in Fig. 2. 
Fig. 4. The real part of the retrieved effective permeability m and permittivity e around the LC resonance of the SRR for the case of purely electric coupling (A) and purely magnetic coupling (B). In (A), m has been multiplied by a factor of 10 to improve visibility. A negative m region is observed for magnetic coupling (B). The resonance/antiresonance coupling between e and m is due to the periodic structure of the metamaterial (14). E, electric field vector; H, magnetic field vector; k, wave vector. 
Fig. 1. Illustration of the analogy between a conventional LC circuit (A), consisting of an inductance L, a capacitance C, and the single SRRs used here (B). l, length; w, width; d, gap width; t, thickness. (C) An electron micrograph of a typical SRR fabricated by electron-beam lithography. The thickness of the gold film is t 0 20 nm. For normal incidence, where the magnetic field vector B lies in the plane of the coil, the electric field vector E of the incident light must have a component parallel to the electric field of the capacitor to couple to the LC circuit. This allows the coupling to be controlled through the polarization of the incident light (Fig. 2).
Topics: Split-ring resonator (64%), Metamaterial (58%), Electric field (57%) ...read more
1,377 Citations
Patent•
23 Sep 2003-
Abstract: An electronic system includes a reader and a remotely powered and remotely interrogated sensor transponder. The sensor transponder includes a coil or an antenna, a switched reactance circuit, a processor, and a sensor. The sensor transponder receives power radiated from the reader to the coil or antenna. The sensor uses the power for sensing. The sensor transponder is capable of processing sensor data in the processor and transmitting the sensor data to the reader using the switched reactance circuit. In one embodiment, the receiver coil or antenna is part of a resonant tank circuit which includes an impedance matching circuit. The impedance matching circuit is connected to the receiver coil or antenna to provide greater current to the sensor or other power-using device than would be available to the sensor or other power-using device if the sensor or other power-using device were connected between the first and second end. The impedance matching circuit can be two or more taps to the coil or antenna.
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Topics: Proximity sensor (62%), Transponder (57%), Antenna (radio) (57%) ...read more
934 Citations
05 Feb 2001-
Abstract: Based on a physical understanding of phase-noise mechanisms, a passive LC filter is found to lower the phase-noise factor in a differential oscillator to its fundamental minimum. Three fully integrated LC voltage-controlled oscillators (VCOs) serve as a proof of concept. Two 1.1-GHz VCOs achieve -153 dBc/Hz at 3 MHz offset, biased at 3.7 mA from 2.5 V. A 2.1-GHz VCO achieves -148 dBc/Hz at 15 MHz offset, taking 4 mA from a 2.7-V supply. All oscillators use fully integrated resonators, and the first two exceed discrete transistor modules in figure of merit. Practical aspects and repercussions of the technique are discussed.
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Fig. 1. BasicLCoscillator. (a) Ideal negative resistance. (b) Nonlinear negative resistance. 
Fig. 3. Model of the switch noise. 
Fig. 4. Role of the current source. (a) No current source. (b) Ideal noiseless current source. 
Fig. 5. Tail-biased VCO with noise filter. (a) Capacitor alone. (b) Complete noise filter. 
Fig. 6. Top-biased VCO with noise filter.
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Topics: Electronic oscillator (57%), Phase noise (57%), Voltage-controlled oscillator (56%) ...read more
876 Citations
Patent•
15 Nov 2001-
Abstract: A device for discharging fastening elements, and a method of preventing a device from discharging fastening devices into human flesh, are disclosed. The device includes a coil proximate a location of discharge, a capacitive element coupled in parallel with the conductive coil to form a resonant tank circuit, an oscillator that drives the tank circuit, a frequency detector, an amplitude control circuit and a processor. The detector detects a frequency of oscillation of the tank circuit as affected by a material proximate the coil. In response to an electrical signal from the oscillator, the control circuit generates a control signal that is provided back to the oscillator. Based upon the frequency and an additional signal functionally related to the control signal, the processor provides an output signal that prevents the device from discharging when the material proximate the coil is human flesh.
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Topics: LC circuit (57%), Electromagnetic coil (56%), Signal (54%) ...read more
637 Citations
Daniel F. Sievenpiper1, James H. Schaffner1, Song Hyok Jae1, Robert Y. Loo1 +1 more•Institutions (1)
Abstract: By covering a metal ground plane with a periodic surface texture, we can alter its electromagnetic properties. The impedance of this metasurface can be modeled as a parallel resonant circuit, with sheet inductance L, and sheet capacitance C. The reflection phase varies with frequency from +/spl pi/ to -/spl pi/, and crosses through 0 at the LC resonance frequency, where the surface behaves as an artificial magnetic conductor. By incorporating varactor diodes into the texture, we have built a tunable impedance surface, in which an applied bias voltage controls the resonance frequency, and the reflection phase. We can program the surface to create a tunable phase gradient, which can electronically steer a reflected beam over +/- 40/spl deg/ in two dimensions, for both polarizations. We have also found that this type of resonant surface texture can provide greater bandwidth than conventional reflectarray structures. This new electronically steerable reflector offers a low-cost alternative to a conventional phased array.
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Topics: LC circuit (57%), Ground plane (54%), Electrical impedance (54%) ...read more
605 Citations