Two‐step, piecewise‐linear SAR ADC with programmable transfer function

2019 ◽  
Vol 55 (8) ◽  
pp. 444-446
Author(s):  
S. Sengupta ◽  
M.L. Johnston
Keyword(s):  
Transfer Function ◽  
Piecewise Linear ◽  
Sar Adc

Study of Non-Linear Theory of Vertical Impact Damping System

2011 ◽  
Vol 66-68 ◽  
pp. 119-124
Author(s):  
Jian Sheng Zhang
Keyword(s):  
Transfer Function ◽  
Analytical Solution ◽  
Linear Theory ◽  
Piecewise Linear ◽  
Dynamical Response ◽  
Compatibility Conditions ◽  
Mechanics Model ◽  
Theory Research ◽  
Vertical Impact ◽  
Impact Damping

A mechanics model of vertical impact damping system was founded based on the experimental device introduced in [1], and interrelated theory research was made on the mechanics model. The analytical solution of system dynamical response was gained using transfer function combining with the system’s neighboring boundary compatibility conditions in the fact of the piecewise linear characteristics of the system.

scholarly journals Implementation of a digital trim scheme for SAR ADCs

2013 ◽  
Vol 11 ◽  
pp. 227-230
Author(s):  
J. Bialek ◽  
A. Wickmann ◽  
F. Ohnhaeuser ◽  
G. Fischer ◽  
R. Weigel ◽  
...  
Keyword(s):  
Transfer Function ◽  
Power Consumption ◽  
Successive Approximation ◽  
Sar Adc ◽  
Production Test ◽  
Digital To Analog Converter ◽  
Analog To Digital ◽  
Capacitor Array ◽  
Capacitor Mismatch ◽  
Analog Converter

Abstract. Successive approximation register (SAR) analog-to-digital Converters (ADC) are based on a capacitive digital-to-analog converter (CDAC) (McCreary and Gray, 1975). The capacitor mismatch in the capacitor array of the CDAC impacts the differential non-linearity (DNL) of the ADC directly. In order to achieve a transfer function without missing codes, trimming of the capacitor array becomes necessary for SAR ADCs with a resolution of more than 12 bit. This article introduces a novel digital approach for trimming. DNL measurements of an 18 bit SAR ADC show that digital trimming allows the same performance as analog trimming. Digital trimming however reduces the power consumption of the ADC, the die size and the required time for the production test.

scholarly journals Bode Plots Revisited: a Software System for Automated Generation of Piecewise Linear Frequency Response Plots

2018 ◽  
Vol 21 (2) ◽  
pp. 76
Author(s):  
Predrag Pejović ◽  
Amela Zeković
Keyword(s):  
Transfer Function ◽  
Frequency Response ◽  
Transfer Functions ◽  
Piecewise Linear ◽  
Automatic Generation ◽  
Analysis Software ◽  
Automated Generation ◽  
Bode Plots ◽  
Poles And Zeros ◽  
Future Work

The paper presents an algorithm for automatic generation of piecewise linear Bode plots. The algorithm is complete in the sense it covers for all posible locations of poles and zeros of transfer functions, including unstable poles and poles and zeroes at the imaginary axis. The starting transfer function is factored into a canonical form, and thirteen elementary transfer function types are defined by their canonical forms. The thirteen elementary transfer function types are shown to be derived from just five generic transfer function types, and piecewise linear Bode plots are defined and depicted for all five of the generic types. For all thirteen elementary transfer function types the nodes they introduce in the piecewise linear plots are specified, as well as the algorithms how they affect the node altitudes. Finally, a three stage algorithm that produces both the Bode plots and the exact numerically computed frequency response plots is described. The algorithm is implemented in a command line based program, illustrated in a filter example, and future work directions are indicated, aiming a graphical user interface and integration of the program to a linear system symbolic analysis software suite.

scholarly journals Mixed-mode Method Used for Pt100 Static Transfer Function Linearization

2021 ◽  
Vol 21 (5) ◽  
pp. 142-149
Author(s):  
Jelena Jovanović ◽  
Dragan Denić
Keyword(s):  
Transfer Function ◽  
Mixed Mode ◽  
Piecewise Linear ◽  
Linearization Method ◽  
Sequential Design ◽  
Nonlinearity Error ◽  
Flash Adc ◽  
Delta Sigma ◽  
Temperature Detector ◽  
Dual Stage

Abstract Pt100 is a resistance temperature detector characterized by a relatively linear resistance/temperature relationship in a narrow temperature range. However, the Pt100 sensor shows a certain degree of static transfer function nonlinearity of 4.42 % in the range between −200 °C and 850 °C, which is unacceptable for some applications. As a solution to this problem, a mixed-mode linearization method based on a special dual-stage piecewise linear ADC design is proposed in this paper. The first stage of the proposed dual-stage piecewise linear ADC is performed with a low-complex and low-power flash ADC of a novel sequential design. The novelty of the proposed sequential design is reflected in the fact that the number of employed comparators is equal to the flash ADC resolution. The second stage is performed with a delta-sigma ADC with a differential input and differential reference. Using the 6-bit flash ADC of novel design and the 24-bit delta-sigma ADC, the nonlinearity error is reduced to 2.6·10−3 %, in the range between −200 °C and 850 °C. Two more ranges are examined, and the following results are obtained: in the range between 0 °C and 500 °C, the nonlinearity error is reduced from 1.99 % to 5·10−4 %, while in the range between −50 °C and 150 °C, the nonlinearity error is reduced from 0.755 % to 2.15·10−4 %.

Radiation Damage of Support Films

1981 ◽  
Vol 39 ◽  
pp. 28-29
Author(s):  
H.A. Cohen ◽  
W. Chiu
Keyword(s):  
Transfer Function ◽  
Low Temperatures ◽  
Carbon Support ◽  
Contrast Transfer Function ◽  
Electron Dose ◽  
Imaging Parameters ◽  
Negative Stain ◽  
Phase Corrections ◽  
Two Parameters ◽  
Medium Dose

The goal of imaging the finest detail possible in biological specimens leads to contradictory requirements for the choice of an electron dose. The dose should be as low as possible to minimize object damage, yet as high as possible to optimize image statistics. For specimens that are protected by low temperatures or for which the low resolution associated with negative stain is acceptable, the first condition may be partially relaxed, allowing the use of (for example) 6 to 10 e/Å2. However, this medium dose is marginal for obtaining the contrast transfer function (CTF) of the microscope, which is necessary to allow phase corrections to the image. We have explored two parameters that affect the CTF under medium dose conditions.Figure 1 displays the CTF for carbon (C, row 1) and triafol plus carbon (T+C, row 2). For any column, the images to which the CTF correspond were from a carbon covered hole (C) and the adjacent triafol plus carbon support film (T+C), both recorded on the same micrograph; therefore the imaging parameters of defocus, illumination angle, and electron statistics were identical.

Possible applications of fraunhofer holography in high resolution electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 222-223 ◽  
Author(s):  
N. Bonnet ◽  
M. Troyon ◽  
P. Gallion
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Transfer Function ◽  
Radiation Damage ◽  
High Resolution Electron Microscopy ◽  
Far Field ◽  
Field Region ◽  
Crystalline Materials ◽  
Resolution Electron ◽  
The Ideal

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

Ultimate resolution and information in electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 496-497
Author(s):  
D. Van Dyck
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Transfer Function ◽  
Information Transfer ◽  
Communication Channel ◽  
Structural Information ◽  
Information Rate ◽  
Noise Power ◽  
Signal Power ◽  
Imaging Device

An (electron) microscope can be considered as a communication channel that transfers structural information between an object and an observer. In electron microscopy this information is carried by electrons. According to the theory of Shannon the maximal information rate (or capacity) of a communication channel is given by C = B log2 (1 + S/N) bits/sec., where B is the band width, and S and N the average signal power, respectively noise power at the output. We will now apply to study the information transfer in an electron microscope. For simplicity we will assume the object and the image to be onedimensional (the results can straightforwardly be generalized). An imaging device can be characterized by its transfer function, which describes the magnitude with which a spatial frequency g is transferred through the device, n is the noise. Usually, the resolution of the instrument ᑭ is defined from the cut-off 1/ᑭ beyond which no spadal information is transferred.

Analytic integration of contrast transfer functions

1988 ◽  
Vol 46 ◽  
pp. 822-823
Author(s):  
Peter Rez
Keyword(s):  
Wave Function ◽  
Transfer Function ◽  
Transfer Functions ◽  
Spherical Aberration ◽  
Continuous Distribution ◽  
Objective Lens ◽  
Direction Parallel ◽  
Scattering Angle ◽  
Analytic Integration ◽  
Image Position

In high resolution microscopy the image amplitude is given by the convolution of the specimen exit surface wave function and the microscope objective lens transfer function. This is usually done by multiplying the wave function and the transfer function in reciprocal space and integrating over the effective aperture. For very thin specimens the scattering can be represented by a weak phase object and the amplitude observed in the image plane is1where fe (Θ) is the electron scattering factor, r is a postition variable, Θ a scattering angle and x(Θ) the lens transfer function. x(Θ) is given by2where Cs is the objective lens spherical aberration coefficient, the wavelength, and f the defocus.We shall consider one dimensional scattering that might arise from a cross sectional specimen containing disordered planes of a heavy element stacked in a regular sequence among planes of lighter elements. In a direction parallel to the disordered planes there will be a continuous distribution of scattering angle.

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