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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01 Feb 1990
TL;DR: In this article, a new test method is described for measuring the source flow ripple and source impedance of positive displacement hydraulic pumps, called the secondary source method, and is based on the analysis of the wave propagation characteristics in a circuit which includes the pump under test and an additional source of fluid-borne noise.
Abstract: The difficulties involved in measuring a pump fluid-borne noise rating are discussed A new test method is described for measuring the source flow ripple and source impedance of positive displacement hydraulic pumps This is called the ‘secondary source’ method, and is based on the analysis of the wave propagation characteristics in a circuit which includes the pump under test and an additional source of fluid-borne noise
75 citations
TL;DR: A basic approach is proposed from the perspective of theoutput impedance to give considerations to both the SHC reduction and dynamic performance improvement, indicating that the output impedance of the front-end dc-dc converter should be designed relatively high at twice the output voltage frequency while relatively low at other frequencies.
Abstract: The instantaneous output power of the two-stage single-phase inverter pulsates at twice the output voltage frequency, resulting in the second-harmonic current (SHC) in the front-end dc-dc converter. In this paper, a basic approach is proposed from the perspective of the output impedance to give considerations to both the SHC reduction and dynamic performance improvement, indicating that the output impedance of the front-end dc-dc converter should be designed relatively high at twice the output voltage frequency while relatively low at other frequencies. According to the proposed approach, one virtual impedance is introduced to be in series with the original output impedance while the other one is in parallel with the intermediate dc bus capacitor. Taking the buck-derived front-end dc-dc converter as an example, the implementation of the virtual impedance is presented, based on which, different control schemes in the previous publications can be synthesized. Finally, a 1-kVA prototype is fabricated in the laboratory and a comparative study is conducted on four different control schemes by both the theoretical analysis and experimental verification.
75 citations
TL;DR: The design of nonlinear droop in dc power distribution systems is studied with special emphasis on load sharing, voltage regulation, system efficiency, and stability, and a generic polynomial expression is presented to unify different droop equations.
Abstract: Linear droop faces the design tradeoff between voltage regulation and load sharing due to cable resistances and sensing errors. Using a larger droop resistance improves load sharing, but requires a wider droop voltage range. In the nonlinear droop, droop resistance is a function of the converter's output current, and its value increases when the output current increases. As a result, the impacts from sensors and cables are reduced. In this paper, the design of nonlinear droop in dc power distribution systems is studied with special emphasis on load sharing, voltage regulation, system efficiency, and stability. After discussing the piecewise linear and nonlinear droop control, a generic polynomial expression is presented to unify different droop equations. The impact of droop on dc system efficiency is analyzed by evaluating cable and power converter losses. The converter's output impedance using nonlinear droop is modeled to analyze the system stability with constant power loads. The selection and design guidelines of nonlinear droop are summarized, considering both the static performance and interaction with load systems. The analysis is verified in 400-V multi-source dc systems. The nonlinear droop is fully distributed as it only needs local information.
75 citations
01 Apr 1946
Abstract: A load having the conjugate impedance of the signal generator to which it is connected receives the maximum amount of power and is said to be matched on the conjugate-image basis. This method of impedance matching, when applied to active and passive four-terminal networks, is shown to be especially suitable for determining the limits of power amplification or loss. In contrast, an analysis on the usual image basis gives these results only if the image impedances happen to be pure resistances. The maximum power gain of a given network and the impedance terminations for achieving it are derived and are expressed in-concise form. The effects of impedance mismatching are likewise treated.
75 citations
01 Jun 2014
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 high gain bulk-driven Miller OTA operating at just 0.25-V power supply in a 130-nm digital CMOS process. The amplifier operates in weak-inversion region with input bulk-driven differential pair with negative resistance source degeneration. In addition, distributed layout configuration is used for all 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.
74 citations