Topic
Output impedance
About: Output impedance is a research topic. Over the lifetime, 11185 publications have been published within this topic receiving 134949 citations.
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Patent•
13 Jan 2000TL;DR: In this paper, the authors proposed a method to detect faults on power lines by measuring the voltage and current at one end of a power line and using these measurements, together with values of series and shunt parameters of the line, to calculate values of voltage and currents at an intermediate point on the line.
Abstract: Faults on power lines are detected by measuring the voltage and current at one end of a power line and using these measurements, together with values of series and shunt parameters of the line, to calculate values of voltage and current at an intermediate point on the line—the so-called “reach point”. At least the calculated voltage is used to determine whether a fault lies within a particular zone on the line. The calculation utilizes a value of a derivative of the measured current with respect to time and is able to take into account the sectioning of a line into discrete lengths corresponding to, for example, overhead and cable sections. To increase accuracy, the line or each discrete section of the line is conceptually divided into subsections each having its own parameter values. In a second aspect, detection of whether a fault lies within a particular zone involves the measurement of the voltage and current at one end of the line both before and after the fault, the calculation of a complex impedance between an intermediate point of the line and a reference point, normally earth, the use of these measured values and values relating to line parameters and to a source impedance at the second end of the line, and the determination of the sign of the complex impedance.
34 citations
TL;DR: In this paper, a modified current conveyor was proposed for current-mode cascading by possessing high output impedance, which was validated through PSPICE simulation using 0.5μ CMOS parameters.
Abstract: This paper presents some new current mode first order all-pass sections with grounded components employing a modified current conveyor. The new circuits are ideal for current-mode cascading by possessing high output impedance. As an application of the circuits, a new quadrature oscillator is also given. The theory is validated through PSPICE simulation using 0.5μ CMOS parameters.
34 citations
TL;DR: An integrated current driver that uses negative feedback to accurately set the output current amplitude into the load and was tested for the detection of cancer sites from postoperative human colon specimens.
Abstract: Bioimpedance measurements are performed in a variety of medical applications including cancer detection in tissue. Such applications require wideband (typically 1 MHz) accurate ac current drivers with high output impedance and low distortion. This paper presents an integrated current driver that fulfills these requirements. The circuit uses negative feedback to accurately set the output current amplitude into the load. It was fabricated in a 0.35-μm complementary metal–oxide–semiconductor (CMOS) process technology, occupies a core area of 0.4 mm2 , and operates from ±2.5-V power supplies. For a maximum output current of 1 mAp-p, the measured total harmonic distortion is below 0.1%, and the variability of the output current with respect to the load is below 0.5% up to 800 kHz increasing to 0.86% at 1 MHz. The current driver was tested for the detection of cancer sites from postoperative human colon specimens. The circuit is intended for use in active electrode applications.
34 citations
Patent•
04 Apr 1973
TL;DR: In this paper, an integrated system including an insulated electrode and an impedance transformer is described for the acquisition of electrocardiographic data, which can be assembled in a small plastic housing.
Abstract: Disclosed is an integrated system including an insulated electrode and an impedance transformer which can be assembled in a small plastic housing and used for the acquisition of electrocardiographic data. The electrode may be employed without a paste electrolyte and may be attached to the body for extended usage without producing skin reaction. The electrode comprises a thin layer of a suitable non-toxic dielectric material preferably deposited by radio frequency sputtering onto a conductive substrate. The impedance transformer preferably comprises an operational amplifier having an FET input stage connected in the unity gain configuration which provides a very low lower cut-off frequency, a high input impedance with a very small input bias current, a low output impedance, and a high signal-to-noise ratio. The electrode may be connected directly into a standard monitoring system normally employed with conventional paste-type electrodes.
34 citations
Patent•
02 Mar 1994
TL;DR: In this article, a broadband switching amplifier with gated switches is described. But the authors do not specify an output stage capable of variable impedance transformation in addition to conventional controlled pulsewidth coupling to produce outpout power without regard for normal power supply or load impedance constraints.
Abstract: A broadband switching amplifier utilizes an output stage capable of variable impedance transformation in addition to conventional controlled pulsewidth coupling to accurately produce outpout power without regard for normal power supply or load impedance constraints. In a preferred embodiment, the present invention charges and discharges a reactance (406) with gated switches (404, 405, 407, 408) in accordance with pulsewidth-modulated signals representative of an input signal. For voltage amplification the reactance is inductive, whereas for current amplification, the reactance is capacitive.
34 citations