Design of Class D Amplifiers Using Zero Crossing Auto Gain Control

2012 ◽  
Vol 198-199 ◽  
pp. 1157-1161
Author(s):  
Hai Shi Wang ◽  
Bo Zhang ◽  
Jiang Sun

This paper proposes a method to control the gain of an amplifier. A 6-bit digital signal is used to control the gain of the amplifier by adjusting the resistance of a potentiometer. The change of the digital signal is allowed to change the gain of the amplifier only if the input signal of the amplifier crosses alternating current (AC) zero. The gain of the amplifier could be reduced or restored, which is based on whether the output signal of the amplifier exceeds a predetermined value or not. The method is verified in a class D amplifier. Road test shows that the method may eliminate the glitch caused by gain change, and the clamp caused by a too large gain.

2008 ◽  
Vol 55 (8) ◽  
pp. 3141-3149 ◽  
Author(s):  
Jiann-Jong Chen ◽  
Ho-Cheng Lin ◽  
Che-Min Kung ◽  
Yuh-Shyan Hwang ◽  
Juing-Huei Su

Author(s):  
Oleksandr Laptiev ◽  
Serhii Yevseiev ◽  
Larysa Hatsenko ◽  
Olena Daki ◽  
Vitaliy Ivanenko ◽  
...  

The paper proposes a fundamentally new approach to the formulation of the problem of optimizing the discretization interval (frequency). The well-known traditional methods of restoring an analog signal from its discrete implementations consist of sequentially solving two problems: restoring the output signal from a discrete signal at the output of a digital block and restoring the input signal of an analog block from its output signal. However, this approach leads to methodical fallibility caused by interpolation when solving the first problem and by regularizing the equation when solving the second problem. The aim of the work is to develop a method for the signal discretization to minimize the fallibility of information recovery to determine the optimal discretization frequency.The proposed method for determining the optimal discretization rate makes it possible to exclude both components of the methodological fallibility in recovering information about the input signal. This was achieved due to the fact that to solve the reconstruction problem, instead of the known equation, a relation is used that connects the input signal of the analog block with the output discrete signal of the digital block.The proposed relation is devoid of instabilities inherent in the well-known equation. Therefore, when solving it, neither interpolation nor regularization is required, which means that there are no components of the methodological fallibility caused by the indicated operations. In addition, the proposed ratio provides a joint consideration of the properties of the interference in the output signal of the digital block and the frequency properties of the transforming operator, which allows minimizing the fallibility in restoring the input signal of the analog block and determining the optimal discretization frequency.A widespread contradiction in the field of signal information recovery from its discrete values has been investigated. A decrease in the discretization frequency below the optimal one leads to an increase in the approximation fallibility and the loss of some information about the input signal of the analog-to-digital signal processing device. At the same time, unjustified overestimation of the discretization rate, complicating the technical implementation of the device, is not useful, since not only does it not increase the information about the input signal, but, if necessary, its restoration leads to its decrease due to the increase in the effect of noise in the output signal on the recovery accuracy. input signal. The proposed method for signal discretization based on the minimum information recovery fallibility to determine the optimal discretization rate allows us to solve this contradiction.


Author(s):  
Nueraimaiti Aimaier ◽  
Nam Ly ◽  
Gabriel Nobert ◽  
Yves Blaquiere ◽  
Nicolas Constantin ◽  
...  

2015 ◽  
Vol 75 (4) ◽  
pp. 1536-1552 ◽  
Author(s):  
Stephen M. Cox ◽  
H. du Toit Mouton
Keyword(s):  

2014 ◽  
Vol 668-669 ◽  
pp. 808-811
Author(s):  
Hui Min Zhang ◽  
Qing Ping Wu ◽  
Zheng Yuan Zhou ◽  
Xun Wang

The low frequency voltage controlled oscillator (VCO) is designed using integrated operational amplifier. The frequency of the output signal of VCO changes with the magnitude of the input signal voltage, and show a linear relationship within a certain range through the experimental test. Experiments show that, under the input of certain amplitude and frequency range of the square wave, triangle wave, saw-tooth wave, the output waveform of VCO respectively is ambulance, fire siren and other kinds of ambulance siren Signal. This innovative design’ cost is low, realized by analog circuit. It can be used in the practice of teaching case, electronic production or development of sound panels.


Author(s):  
Niels Poulsen ◽  
Henrik Niemann

Active Fault Diagnosis Based on Stochastic TestsThe focus of this paper is on stochastic change detection applied in connection with active fault diagnosis (AFD). An auxiliary input signal is applied in AFD. This signal injection in the system will in general allow us to obtain a fast change detection/isolation by considering the output or an error output from the system. The classical cumulative sum (CUSUM) test will be modified with respect to the AFD approach applied. The CUSUM method will be altered such that it will be able to detect a change in the signature from the auxiliary input signal in an (error) output signal. It will be shown how it is possible to apply both the gain and the phase change of the output signal in CUSUM tests. The method is demonstrated using an example.


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