Negative feedback

2021 ◽  
pp. 363-377
Author(s):  
Geoffrey Brooker

Negative feedback is an essential constituent of any control system. It is illustrated for the case of an electronic voltage amplifier. Formal definitions are given of positive and negative feedback. Feedback can be used to adjust the amplifier's frequency response. Distortion, meaning generation of new and unwanted frequencies (harmonics, sums, differences), is reduced by a factor equal to the “return difference”.

2009 ◽  
Vol 60-61 ◽  
pp. 180-184
Author(s):  
Bin Yan ◽  
Wei Zheng Yuan ◽  
Yi Ting Yu ◽  
Lan Lan Wang ◽  
Da Yong Qiao ◽  
...  

Based on a new micro programmable grating with changeable blazed angle, the control system was recently designed and developed, enabling the normal operation for the fabricated grating. The basic requirements for the control system are high reliability, efficiency and miniaturization. This paper presents the specific design objectives for the control system according to the grating’s operation characteristics. The whole control system contains three key modules—generator & communication module, high-voltage amplifier module and computer software module. Generator & communication module includes a high-performance microcontroller (C8051F020), a D/a converter (AD7305) and universal serial bus (USB) interface. As for the considered performances, PA69 is complete capable of magnifying the driving voltage signals to drive the grating in high-voltage amplifier module. After the development of the control system, an experiment was performed for investigating the dynamic frequency response of the grating. In conclusion, it has the advantages of wide output of voltage, high frequency response, driving ability in wide capacitive load range and real-time control properties. Hence, it is appropriate for controlling MEMS programmable grating in complicated and dynamic conditions.


2019 ◽  
Vol 120 ◽  
pp. 253-261
Author(s):  
Shufeng Hao ◽  
Chongyang Shi ◽  
Zhendong Niu ◽  
Longbing Cao

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