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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TL;DR: A miniaturized electrical impedance tomography system that can image the electrical conductivity distribution within a two-dimensional cell culture and provides a non-invasive lab-on-a-chip technology for spatially mapping the electrical properties of single cells, which would be significant and useful for diagnostic and clinical applications.
89 citations
Patent•
05 Feb 1999TL;DR: In this paper, the ratio of reflected power to forward power is obtained for one frequency, and then the frequency is changed in the other direction, if the new ratio is smaller, the frequency can be changed again in the same direction, but if larger, then a new frequency is needed to be changed in another direction.
Abstract: An RF plasma system employs frequency tuning to change the frequency of an RF
generator (14) within a frequency range to match the impedance of a plasma chamber (18).
Forward power and reflected power magnitudes are obtained from a bidirectional sensor (16).
The ratio of reflected power to forward power is obtained for one frequency, and then the
frequency is changed. The tuning algorithm compares the ratio of reflected to forward power
at the new frequency with the ratio obtained earlier. If the new ratio is smaller, the frequency
is changed again in the same direction, but if larger, then the frequency is changed in the other
direction. These steps are iterated until the ratio of reflected to forward power reaches a
minimum. The tuning algorithm can be implemented in hardware or in software.
89 citations
TL;DR: In this article, an extended impedance-based fault location algorithm for underground distribution systems is presented, which calculates the apparent impedance using only local voltage and current data and provides an iterative algorithm to compensate the typical capacitive component current of underground cables.
89 citations
TL;DR: This work presents a power- and area-efficient three-stage amplifier that is able to drive a large capacitive load and achieves an optimized tradeoff between the frequency and the Q-factor of the complex poles.
Abstract: This work presents a power- and area-efficient three-stage amplifier that is able to drive a large capacitive load. Removing the inner Miller capacitor and employing cascode Miller compensation in the outer compensation loop could extend the complex-pole frequency of a three-stage amplifier, but result in a high Q-factor. A local impedance attenuation block consisting of a series RC network is proposed to control the complex poles. This block attenuates the high-frequency resistance at the second-stage output and achieves an optimized tradeoff between the frequency and the Q-factor of the complex poles. As the low-frequency resistance remains unchanged, a high dc gain is maintained. Implemented in 0.13 $\mu$ m CMOS process, the proposed design occupies an area of 0.0032 mm 2 and consumes a quiescent current of 10.5 $\mu$ A. When driving a 560 pF capacitive load, it achieves a unity-gain frequency of 3.49 MHz, an average slew rate of 0.86 V/ $\mu$ s, and an average settling time of 0.9 $\mu$ s.
89 citations
Patent•
09 Sep 1998
TL;DR: In this article, the capacity of the variable capacitor is controlled and the impedance is matched, by simply controlling the applied voltage across the non-linear dielectric thin film, which makes it possible to cut down the impedance matching device in size and cost, compared to an arrangement incorporating a capacitor and a coil for adjustment, and facilitates a manufacturing process.
Abstract: An impedance matching device includes a variable capacitor constituted by a non-linear dielectric thin film and an upper electrode disposed on a lower electrode formed on a substrate. The non-linear dielectric thin film is formed by a deposition, screen-printing, electroplating, or other technique, and changes its relative dielectric constant according to applied voltage. Therefore, the capacity of the variable capacitor is controlled and the impedance is matched, by simply controlling the applied voltage across the non-linear dielectric thin film. Consequently, the arrangement makes it possible to cut down the impedance matching device in size and cost, compared to an arrangement incorporating a capacitor and a coil for adjustment, effects a much simpler matching operation, and facilitates a manufacturing process.
88 citations