Topic
Frequency response
About: Frequency response is a research topic. Over the lifetime, 25705 publications have been published within this topic receiving 332249 citations.
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TL;DR: In this paper, the frequency response of a group of 1.3 μm InGaAsP vapor-phase-regrown buried heterostructure lasers of various cavity lengths is analyzed by fitting the measured response curves.
Abstract: The frequency response of a group of 1.3 μm InGaAsP vapor-phase-regrown buried heterostructure lasers of various cavity lengths is analyzed by fitting the measured response curves. The dependence of resonant frequency f 0 and damping rate \Gamma on bias power is determined. The differential gain coefficient for InGaAsP is determined as 3.5 \times 10^{-16} cm2. The damping rate is found to be proportional to the square of the resonant frequency with a proportionality factor which is independent of device geometry and facet reflectivity. The existence of such a universal relationship between \Gamma and f 0 and the observed magnitude of the damping rate is explained by the interband relaxation model of nonlinear gain.
306 citations
TL;DR: In this article, a complex least squares fitting of small-signal frequency response data at various immittance levels is presented, and a number of actual equivalent circuits used in the past for both liquid and solid electrolytes are presented and compared.
305 citations
TL;DR: In this paper, a new method for designing low profile frequency selective surfaces (FSS) with second-order bandpass responses is presented, which utilizes non-resonant subwavelength constituting unit cells with unit cell dimensions and periodicities in the order of 0.15 lambda 0.30.
Abstract: In this study, a new method for designing low profile frequency selective surfaces (FSS) with second-order bandpass responses is presented. The FSSs designed using this technique utilize non-resonant subwavelength constituting unit cells with unit cell dimensions and periodicities in the order of 0.15lambda0. It is demonstrated that using the proposed technique, second-order FSSs with an overall thickness of lambda0/30 can be designed. This is considerably smaller than the thickness of second-order FSSs designed using traditional techniques and could be particularly useful at lower frequencies with long wavelengths. To facilitate the design of this structure, an equivalent circuit based synthesis method is also presented in this paper. Two bandpass FSS prototypes operating at X-band are designed, fabricated, and tested. A free space measurement setup is used to thoroughly characterize the frequency responses of these prototypes for both the TE and TM polarizations and various angles of incidence. The frequency responses of these structures are shown to have a relatively low sensitivity to the angle of incidence. Principles of operation, detailed design and synthesis procedure, and measurement results of two fabricated prototypes are presented and discussed in this paper.
302 citations
TL;DR: In this article, the effects of pole zero pairs (doublets) on the frequency response and settling time of operational amplifiers were explored using analytical techniques and computer simulation, and it was shown that doublets which produce only minor changes in circuit frequency response can produce major changes in settling time.
Abstract: The effects of pole-zero pairs (doublets) on the frequency response and settling time of operational amplifiers are explored using analytical techniques and computer simulation. It is shown that doublets which produce only minor changes in circuit frequency response can produce major changes in settling time. The importance of doublet spacing and frequency are examined. It is shown that settling time always improves as doublet spacing is reduced whereas the effect of doublet frequency is different for 0.1 and 0.01 percent error bands. Finally it is shown that simple analytical formulas can be used to estimate the influence of frequency doublets on amplifier settling time.
300 citations
TL;DR: In this article, an ultrasonic sensor that is able to measure the distance from the ground of selected points of a motor vehicle is described, which is based on the measurement of the time of flight of a ultrasonic pulse which is reflected by the ground.
Abstract: This paper describes an ultrasonic sensor that is able to measure the distance from the ground of selected points of a motor vehicle. The sensor is based on the measurement of the time of flight of an ultrasonic pulse, which is reflected by the ground. A constrained optimization technique is employed to obtain reflected pulses that are easily detectable by means of a threshold comparator. Such a technique, which takes the frequency response of the ultrasonic transducers into account, allows a sub-wavelength detection to be obtained. Experimental tests, performed with a 40 kHz piezoelectric-transducer based sensor, showed a standard uncertainty of 1 mm at rest or at low speeds; the sensor still works at speeds of up to 30 m/s, although at higher uncertainty. The sensor is composed of only low cost components, thus being apt for first car equipment in many cases, and is able to self-adapt to different conditions in order to give the best results.
298 citations