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Brad Albing

Poles & Zeroes: I Understand, Mostly

Brad Albing
Brad Albing
Brad Albing
3/28/2013 2:18:35 PM
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Blogger
Re: The good old days of Poles and Zeroes
That's good advice. There are easy to use sim-programs that let you tinker w/ component values and watch what happens to the pole and zero locations and to the freq and phase response. Sweet.

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davebirdieee
davebirdieee
2/1/2013 1:28:59 AM
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Newbie
Re: Neat Link - What about oscillators?
Yes, I've done bulb, and JFET to stabilize a Wien Bridge. The quadrature oscillator is easy to regulate with a hard limit and the design equations are so easy that you know exactly what you are doing. Discrete transistor type phase shift oscillators and RC oscillators can be a bear though. Those are low Q, which has something to do with it...


Dave

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Brad Albing
Brad Albing
1/31/2013 8:32:55 PM
User Rank
Blogger
Re: Neat Link - What about oscillators?
Dave - interesting idea. Don't know if it can be done beyond tweaking the gain of the amplifier (that is part of the oscillator) with an active element (think JFET or incandescent lightbulb). We'll see if anyone else has a suggestion.


Meanwhile, I do plan on tweaking my list of key words to make it more comprehensive and suitably specific.

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davebirdieee
davebirdieee
1/31/2013 6:45:09 PM
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Newbie
Neat Link - What about oscillators?
The MIT link is a really good link, especially in understanding sinudoidal oscillators. But, many oscillators depend on the natural limitations of the non-linear circuit elements to limit the amplitude. That's fine when it happens, but sometimes one would like to design in some form of guaranteed starting, and amplitude regulation. One concept is to regulate the position of the real part of the system response back and forth across the imaginary axis to make the response maintain itself exactly on the axis. Question is, this is inherently non-linear. At least one can't usefully use the existing system respsonse analytically to do it. At least I don't know how to do that. Maybe others do.

For those who design analog/linear sinusoidal oscillators, anyone who could point out some useful links as to how to handle the amplitude regulation would be highly appreciated.

Thanks,

Dave

BTW, we need some more tags to get linear oscillators. This seems to be a forgotten topic.

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Man21
Man21
1/31/2013 7:43:20 AM
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Newbie
Poles and Zeros
Dear Brad,

Many years ago I realised the need to understand circuit analysis better and found the best way to learn, understand and remember the techniques was to write a book. This really does illuminate ones lack of understanding. When you have to write a coherent account the gaps become apparent. The present version is found under ISBN 978-0-521-69780-5 and you will find a slightly expanded diagram, similar to your quote from the MIT note, on p67. There are examples of how use of this representation of circuit properties helps in understanding of circuit function and design.

Scott Hamilton.

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PierreBTOL
PierreBTOL
1/30/2013 11:57:19 AM
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Newbie
Useful
Thank you Brad for this article and valuable MIT link !

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shovelit
shovelit
1/29/2013 3:21:33 PM
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Newbie
Re: The good old days of Poles and Zeroes
Yes. The Z transform is done to obtain the co-effecients to be used in the digital implementation of the filter. It would be complete if we design an anolog hi -pass filter. Let's say 60 Hz. Then bring the design over into the digital realm with a sampling rate of 40khz. This meets the nyguist criteria for the audio range, but we might have to use a decimated digital filter due to the lo range. OK, you start! Lets make it a 2 pole filter with 12 db roll off.

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Clyde
Clyde
1/29/2013 1:33:58 PM
User Rank
Newbie
Re: The good old days of Poles and Zeroes
Digital filtering requires the use of poles and zeros in the Z-domain. Or, am I incorrect?

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shovelit
shovelit
1/28/2013 3:56:08 PM
User Rank
Newbie
The good old days of Poles and Zeroes
True, I haven't used the concept of poles and zeroes since I no longer do analog filter design. Basically, it was a great tool for visualizing the stability of a circuit.Adding a capacitor would move the poles into a stable region. The only thing that really stuck in my mind is don't go outside the unit circle.

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