Topic
Electrical impedance
About: Electrical impedance is a research topic. Over the lifetime, 36015 publications have been published within this topic receiving 371891 citations. The topic is also known as: electrical impedance & complex impedance.
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Patent•
21 Aug 2002TL;DR: In this paper, a bi-directional communication system includes a driver capable of controlling a slew rate of transmitted data signals, which is maintained constant as data is driven from the data driver.
Abstract: A bi-directional communication system includes a driver capable of controlling a slew rate of transmitted data signals. Impedance matching can be provided to match an impedance of a driver circuit to an impedance of a communication line. The impedance is maintained constant as data is driven from the data driver. The data receiver circuit can adjust a reference voltage in response to simultaneously transmitted data. The slew rate of the receiver circuit trip point is controlled to maintain adequate noise margin during operation. Both the receiver and driver circuits can be controlled using a delay line circuit.
70 citations
Patent•
IBM1
TL;DR: In this article, the authors proposed a method for reducing the reflected power in a radio frequency amplifier, where a first directional coupler divides the radio frequency signal to first and second quadrature signals.
Abstract: Apparatus and method for reducing reflected power in a radio frequency amplifier. A first directional coupler divides the radio frequency signal to first and second quadrature signals. First and second amplifiers amplify each of the quadrature signals. A second directional coupler combines signals from the amplifiers to produce a combined signal. A third directional coupler samples a portion of the reflected power received on the second directional coupler output. A control signal is derived from sampling the reflected power. A variable load impedance connected to the remaining output port of the second directional coupler has an impedance value which changes with respect to a control signal and the impedance is varied so as to substantially match the impedance received by the first output port.
70 citations
TL;DR: An impedance measurement technique based on the use of a personal computer, two digitizing channels and the application of four-parameter sine-fitting algorithms to estimate amplitude, phase, offset and frequency of the voltages across the impedance under measurement and of a reference impedance is described.
70 citations
Patent•
28 Jan 2005TL;DR: In this paper, a quadrature mixer with an LO input is provided, where the mixer interacts with the output impedance such that an impedance presented at the signal input is high for signals at FSIG if FSIG is a predetermined signal frequency, and low at other frequencies.
Abstract: A quadrature mixer with an LO input is provided. The quadrature mixer receives a signal having a frequency FLO and a signal input having a frequency FSIG and has an output that comprises an output impedance that is high at frequencies of [FLO-FSIG] and [FLO + FSIG] and low at other. A mixer coupled to the output impedance interacts with the output impedance such that an impedance presented at the signal input is high for signals at FSIG if FSIG is a predetermined signal frequency, and low at other frequencies.
70 citations
Patent•
23 Mar 1989TL;DR: In this paper, a tuned oscillator circuit (14) with an inductive impedance simulates a resonant inductive-capacitive circuit not including an inductor and provides a signal with a period which is a function of the variable capacitance value, and of the applied fluid pressure.
Abstract: A pressure sensor (10) includes a pair of capacitors (C1, C2), at least one of which is variable responsive to an applied fluid pressure (DELTAP) to predictably change capacitance value. A tuned oscillator circuit (14) having an inductive impedance includes the variable capacitor and simulates a resonant inductive-capacitive circuit not including an inductor. The tuned circuit (14) oscillates to provide a signal with a period which is a function of the variable capacitance value, and of the applied fluid pressure. Additional elements are provided for precise measurement of the variable signal, correction for temperature effects, correction of measurement aberrations, and production of an output signal in a preferred format.
70 citations