4. Basic filter blocks in cascade synthesis
Active filters using cascade synthesis are built using one or more second-order cells plus a first-order cell when the degree of the transfer function is odd. To create such cells, amplifiers, resistors and capacitors are combined in three types of looped combinations:
single or multiple negative feedback loops ;
positive feedback loops ;
feedforward loops, to create transmission zeros.
Often, two or three of these types of loop are used simultaneously.
This paragraph presents the elementary blocks based on these principles.
4.1 First-order cells
The general form of their transfer function...
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Basic filter blocks in cascade synthesis
Production of complex active filters
Bibliography
References
Software
The calculation of an active filter is divided into two distinct parts:
transfer function calculation ;
calculation of the numerical values of the elements included in the production diagram.
Filter transfer functions can be calculated using general mathematical software such as MATLAB, Mathematica or Mathcad,...
Manufacturers, constructors
Analog Device http://www.analog.com/
Burr Brown (see Texas Instrument)
Linear Technology http://www.linear.com/
Maxim http://www.maxim-ic.com/
...
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