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PSoC Creator & Designer Software

ETRO_SSN583
Esteemed Contributor

This post should really belong on a section of forum for general electrical

   

issues, I am requesting a new topic area be added to forum. That being said

   

see the video discussed below, very informative.

   

 

   

Take a look at this youtube video on C dependence on bias voltage.

   

 

   

    

   

          https://www.youtube.com/watch?v=2MQyQUkwmVMk

   

 

   

C dependence on its applied V, both DC and RMS, not new but rarely discussed,

   

or shown in datasheets in any meaningful way. Kind of like the single rail input

   

stage crossover distortion of OpAmps, rarely highlighted in datasheets.

   

 

   

Even more troubling note the discussion on how the C does not follow its own exponential

   

behaviour, gets very non linear. In a control loop, like use as a S/H cap, stability issues

   

come to mind, let alone accuracy of loop.

   

 

   

Needless to say if we have any of this stuff in signal path and are trying to achieve 20 bits

   

with DelSig, good luck.

   

 

   

Qualify your capacitors in short is the advice. In the very least, for bulk bypass, consider

   

specifiying values 2 X or more than what you need because of typical loss of C due to bias

   

voltage.

   

 

   

Regards, Dana.

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Anonymous
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Some related reading here as well

   

http://www.cliftonlaboratories.com/capacitor_voltage_change.htm

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ETRO_SSN583
Esteemed Contributor

Excellent treatment on the topic, thanks H L.

   

 

   

Regards, Dana.

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Anonymous
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