scholarly journals Fractional-Order Phase Shifters with Constant Magnitude Frequency Responses

2019 ◽  
Vol 25 (5) ◽  
pp. 25-30 ◽  
Author(s):  
Roman Sotner ◽  
Lukas Langhammer ◽  
Jan Jerabek ◽  
Peter A. Ushakov ◽  
Tomas Dostal
Keyword(s):  
Fractional Order ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Phase Shifters ◽  
Phase Shifting ◽  
Variable Gain ◽  
Frequency Responses ◽  
Straightforward Method ◽  
Constant Magnitude ◽  
Constant Phase Elements

This contribution presents and experimentally analyzes the idea how to reach the constant magnitude as well as the phase response in the fractional-order (FO) phase when shifting two-ports. The straightforward method employing the automatic gain control circuit (AGC) in a cascade after so-called constant phase block approximating FO integrator or differentiator is studied. The variable gain amplifier utilized in AGC and simple RC-based FO constant phase elements (approximating capacitors with order alpha = 1/4 and alpha = 1/2 as an example) connected in the feedback of operational amplifier-based integrator are established in the experimental setup. The operation indicated in three decades (between 100 Hz and 100 kHz) is evaluated. The known solutions of the standard FO phase shifting circuits are discussed and generally compared with the features obtained in this paper, together with the supposed effects of AGC on their performances.

Input Stimuli for Obtaining Frequency Responses of Automatic Gain Control Hearing Aids

1989 ◽  
Vol 32 (1) ◽  
pp. 189-194 ◽  
Author(s):  
David A. Preves ◽  
Lucille B. Beck ◽  
Edwin D. Burnett ◽  
Harry Teder
Keyword(s):  
Frequency Response ◽  
Hearing Aids ◽  
Input Signal ◽  
Pure Tone ◽  
Automatic Gain Control ◽  
Broad Band ◽  
Gain Control ◽  
Response Curves ◽  
Frequency Responses ◽  
Band Noise

Developing a family of frequency response curves for AGC types of hearing instruments using swept pure tones at varying input levels often produces erroneous results. This problem is caused by exceeding the threshold for activating the AGC circuit at some frequencies but not at other frequencies during the pure-tone sweep, thereby producing a different frequency response from that which would be obtained with a complex input signal such as speech-shaped noise. This measurement artifact may be minimized by ensuring that the threshold for activating the AGC circuit is either always exceeded or never exceeded during the development of a frequency response curve. Three input signals are compared for developing a family of frequency responses for an AGC hearing aid: (1) swept pure tone, (2) swept pure tone with bias tone added, and (3) shaped broad-band noise. The shaped broad-band noise appears to be the input signal of choice.

Optimal Design of Broadband and Large Dynamic Range IF AGC Circuit

2013 ◽  
Vol 722 ◽  
pp. 194-197
Author(s):  
Ming Fei Wang ◽  
Peng Cao ◽  
Hui Yong Sun ◽  
Ming Jin Xu
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Intermediate Frequency ◽  
Large Dynamic Range ◽  
Wireless Receiver ◽  
Key Technology ◽  
Variable Gain ◽  
Logarithmic Amplifier ◽  
And Performance

The bandwidth and the dynamic range is the critical performance parameter of IF AGC (Intermediate Frequency Automatic Gain Control) in wireless receiver. In order to design broadband and large dynamic range IF AGC circuit, the main functions and performance of the VGA (Variable Gain Amplifier) AD8367 and the logarithmic amplifier AD8318 are analyzed. A kind of a broadband large dynamic range IF AGC module is designed by using these two chips. Detail circuit is provided; key technology of AGC module is analyzed and the actual testing results are offered. Compared to the traditional AGC circuit, the module is simple; it has small size and obvious advantages in broadband and large dynamic range.

Video-Enhanced Microscopy--Better Visibility of Plant Cell Structures

1982 ◽  
Vol 40 ◽  
pp. 182-185
Author(s):  
N.S. Allen ◽  
R.D. Allen
Keyword(s):  
Diffraction Pattern ◽  
Theoretical Basis ◽  
Numerical Aperture ◽  
Gain Control ◽  
Control Unit ◽  
Camera Control ◽  
Variable Gain ◽  
Contrast Method ◽  
Fine Detail ◽  
Cell Structures

Various methods of video-enhanced microscopy combine TV cameras with light microscopes creating images with improved resolution, contrast and visibility of fine detail, which can be recorded rapidly and relatively inexpensively. The AVEC (Allen Video-enhanced Contrast) method avoids polarizing rectifiers, since the microscope is operated at retardations of λ/9- λ/4, where no anomaly is seen in the Airy diffraction pattern. The iris diaphram is opened fully to match the numerical aperture of the condenser to that of the objective. Under these conditions, no image can be realized either by eye or photographically. Yet the image becomes visible using the Hamamatsu C-1000-01 binary camera, if the camera control unit is equipped with variable gain control and an offset knob (which sets a clamp voltage of a D.C. restoration circuit). The theoretical basis for these improvements has been described.

A CMOS Wideband Variable Gain LNA with Novel Gain Control Method

2010 ◽  
Vol 32 (11) ◽  
pp. 2772-2775
Author(s):  
Fei-hua Chen ◽  
Xin-zhong Duo ◽  
Xiao-wei Sun
Keyword(s):  
Control Method ◽  
Gain Control ◽  
Variable Gain

scholarly journals Measuring Current in a Power Converter Using Fuzzy Automatic Gain Control

2021 ◽  
Vol 11 (13) ◽  
pp. 5793
Author(s):  
Bartosz Dominikowski
Keyword(s):  
High Resolution ◽  
Fuzzy Controller ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Measurement Range ◽  
Power Converter ◽  
Current Measurement ◽  
Dc Power ◽  
Programmable Gain ◽  
Electric Loads

The accuracy of current measurements can be increased by appropriate amplification of the signal to within the measurement range. Accurate current measurement is important for energy monitoring and in power converter control systems. Resistance and inductive current transducers are used to measure the major current in AC/DC power converters. The output value of the current transducer depends on the load motor, and changes across the whole measurement range. Modern current measurement circuits are equipped with operational amplifiers with constant or programmable gain. These circuits are not able to measure small input currents with high resolution. This article proposes a precise loop gain system that can be implemented with various algorithms. Computer analysis of various automatic gain control (AGC) systems proved the effectiveness of the Mamdani controller, which was implemented in an MCU (microprocessor). The proposed fuzzy controller continuously determines the value of the conversion factor. The system also enables high resolution measurements of the current emitted from small electric loads (≥1 A) when the electric motor is stationary.

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