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•
22 Feb 1993
TL;DR: In this article, the power output of an ultrasonic generator to a transducer is controlled by a variable impedance network circuit which is interposed between the generator and the transducers.
Abstract: Apparatus and a method for controlling the power output of an ultrasonic generator to a transducer includes a variable impedance network circuit which is interposed between the generator and the transducer. Sensing circuits and a microprocessor are coupled to the input of the transducer so that the total impedance ZT, the transducer impedance in free air ZFA and the load impedance ZL may be calculated and the network impedance ZNW may be set for a bonding operation to maintain the power level PL or the impedance ZL at a desired predetermined level.
147 citations
TL;DR: A 60-dB gain bulk-driven Miller OTA operating at 0.25-V power supply in the 130-nm digital CMOS process can help overcome some of the constraints imposed by nanometerCMOS process for high performance analog circuits in weak inversion region.
Abstract: This paper presents a 60-dB gain bulk-driven Miller OTA operating at 0.25-V power supply in the 130-nm digital CMOS process. The amplifier operates in the weak-inversion region with input bulk-driven differential pair sporting positive feedback source degeneration for transconductance enhancement. In addition, the distributed layout configuration is used for all the transistors to mitigate the effect of halo implants for higher output impedance. Combining these two approaches, we experimentally demonstrate a high gain of over 60-dB with just 18-nW power consumption from 0.25-V power supply. The use of enhanced bulk-driven differential pair and distributed layout can help overcome some of the constraints imposed by nanometer CMOS process for high performance analog circuits in weak inversion region.
147 citations
TL;DR: In this article, the authors focused on the use of surface treatments as a way to decrease the active material/current collector impedance of carbon/carbon supercapacitors, which is the real part of the impedance at a given frequency is called equivalent series resistance.
Abstract: Power improvement in supercapacitors is mainly related to lowering the internal impedance The real part of the impedance at a given frequency is called ESR (equivalent series resistance) Several contributions are included in the ESR: the electrolyte resistance (including the separator), the active material resistance (with both ionic and electronic parts) and the active material/current collector interface resistance The first two contributions have been intensively described and studied by many authors The first part of this paper is focused on the use of surface treatments as a way to decrease the active material/current collector impedance Al current collector foils have been treated following a two-step procedure: electrochemical etching and sol-gel coating by a highly-covering, conducting carbonaceous material It aims to increase the Al foil/active material surface contact leading to lower resistance In a second part, carbon-carbon supercapacitor impedance is discussed in term of complex capacitance and complex power from electrochemical impedance spectroscopy data This representation permits extraction of a relaxation time constant that provides important information on supercapacitor behaviour The influence of carbon nanotubes addition on electrochemical performance of carbon/carbon supercapacitors has also been studied by electrochemical impedance spectroscopy
146 citations
TL;DR: In this article, the frequency dependence of MESFET drain impedance at low frequencies has been measured and a simple model which simulates this behaviour is also proposed, which is based on the model proposed in this paper.
Abstract: Measurements showing the frequency dependence of MESFET drain impedance at low frequencies have been performed. A simple model which simulates this behaviour is also proposed.
146 citations
Patent•
15 Mar 1988TL;DR: In this paper, a device for detecting the residual capacity of a battery comprises a battery current measuring circuit, a battery voltage measuring circuit and a converting circuit for converting the measured current into a voltage value, based on the internal impedance of the battery, and a comparator circuit for comparing the conversion voltage value with the measured voltage.
Abstract: A device for detecting the residual capacity of a battery comprises a battery current measuring circuit for measuring battery current, a battery voltage measuring circuit for measuring battery voltage, a converting circuit for converting the measured current into a voltage value, based on the internal impedance of the battery, and a comparator circuit for comparing the conversion voltage value with the measured voltage. When the measured voltage is smaller than the conversion voltage value, the comparator circuit operates a battery residual-capacity detect signal indicating that the residual capacity of the battery is small.
144 citations