The model text shows that the model is limited to simulating a maximum of a ninth-order filter, which is made up of one first-order section and four second-order sections. It is often considered that a ninth-order filter is adequate for most applications. The filter model can easily be increased to simulate filters greater than 9th order by adding second-order sections. The transfer functions are specified through. FUNC statements. The parameters a1 through a4 and b1 through b4 determine which filter sections of the model are selected by using a simple selection algorithm, based on the order of the filter specified by the user.
The selection algorithm is implemented using. PARAM statements as shown in the model text. The filter order is defined by the subcircuit parameter, ORD. PARAM statements. These values are looked up automatically given the order of the filter. These subcircuit parameters are given default values, which are arbitrarily set to 1. They will be changed to the required cutoff frequency and order when the subcircuit is called. To illustrate the use of the models, consider the following example.
Here, the Butterworth lowpass filter model is used to obtain a family of curves for second- through ninth-order responses. Assume the filter has a cutoff frequency of 10 kHz. Using Capture, the following circuit is drawn. Finally, a VDB voltage marker is placed on the output node to view the results.
The PSpice simulation consists of a point linear AC sweep and a parametric analysis. There alternate topologies usually require 2 to 4 op amps per stage. The higher loop gains and buffering of nodes results in more precise responses.
FilterPro places a red asterisk alongside any filter response where it detects the Q will be greater than The original intent was to have a message indicating that a lower Q alternative should be considered, but somewhere along the way that message was lost.
I hope this helps provide some guidance. PA - Linear Applications Engineering. Site Search User. Amplifiers Amplifiers forum. Mentions Tags More Cancel.
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Learn more. Asked 1 year, 7 months ago. Active 1 year, 7 months ago. Viewed 99 times. Does anyone know what I'm doing wrong in Pspice? How can I solve my Pspice settings to get a correct result? Why is there a dB attenuation in the passband? Michiel Reyntjens. Michiel Reyntjens Michiel Reyntjens 91 5 5 bronze badges. AC command. OP, your simulation uses linear frequency axis, but you need it logarithmic. Are you allowed to use a filter design program?
This would be the best and easiest way for designing such a filter. SunnySkyguy said:. I don't have knowlodge much. I can use pspice. If This filter will be designed, Can I connect in series 2th low pass and 3th high pass? So - what do you really need? Last edited: Dec 10, Narayanan Junior Member level 3. Next, order of filter will be based on your stopband rejection level. Similar threads A. Analog Circuit Design.
Third order butterworth bandpass filter Started by sherif96 Apr 12, Replies: 5. Help on Butterworth bandpass filter design Started by nego Apr 30, Replies:
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