Beat‐less algorithm based on dual‐frequency compensation in railway traction applications

A Dual Frequency Compensation Technique to Improve Stability and Transient Response for a Three Stage Low-Drop-Out Linear Regulator

Mathematical Modelling and Engineering Problems ◽

10.18280/mmep.080208 ◽

2021 ◽

Vol 8 (2) ◽

pp. 219-229

Author(s):

Anass Slamti ◽

Youness Mehdaoui ◽

Driss Chenouni ◽

Zakia Lakhliai

Keyword(s):

Transient Response ◽

Low Voltage ◽

Drop Out ◽

Frequency Compensation ◽

Dual Frequency ◽

Load Current ◽

Voltage Range ◽

Dominant Pole ◽

Compensation Technique ◽

Ldo Regulator

A novel internal compensation technique named dual frequency compensation is proposed to improve the stability and the transient response of the on-chip output capacitor three stage low-drop-out linear voltage regulator (LDO). It exploits a combination of amplification and differentiation to sufficiently separate the dominant pole from the first non-dominant pole so that the latter is located after the unity gain frequency regardless of the load current value. The proposed LDO regulator is analyzed, designed, and simulated in standard 0.18 µm low voltage CMOS technology. The presented LDO regulator delivers a stable voltage of 1.2 V for an input supply voltage range of 1.35-1.85 V with a maximum line deviation of 4.68mV/V and can supply up to 150mA of the load current. The maximum transient variation of the output voltage is 54.5 mV when the load current pulses from 150mA to 0mA during a fall time of 1µs. The proposed LDO regulator has a low figure of merit compared with recent LDO regulators.

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Correction of the contrast transfer function to determine the radial density distribution of frozen-hydrated tobacco mosaic virus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123088 ◽

1992 ◽

Vol 50 (1) ◽

pp. 536-537

Author(s):

Michael F. Smith ◽

John P. Langmore

Keyword(s):

Transfer Function ◽

Phase Contrast ◽

Heavy Atom ◽

Biological Molecules ◽

Frequency Compensation ◽

Contrast Transfer Function ◽

High Background ◽

Low Contrast ◽

Radial Density Distribution ◽

Excellent Preservation

The purpose of image reconstruction is to determine the mass densities within molecules by analysis of the intensities within images. Cryo-EM offers this possibility by virtue of the excellent preservation of internal structure without heavy atom staining. Cryo-EM images, however, have low contrast because of the similarity between the density of biological material and the density of vitreous ice. The images also contain a high background of inelastic scattering. To overcome the low signal and high background, cryo-images are typically recorded 1-3 μm underfocus to maximize phase contrast. Under those conditions the image intensities bear little resemblance to the object, due to the dependence of the contrast transfer function (CTF) upon spatial frequency. Compensation (i.e., correction) for the CTF is theoretically possible, but implementation has been rare. Despite numerous studies of molecules in ice, there has never been a quantitative evaluation of compensated images of biological molecules of known structure.

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