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Problem with LM139 comparators output

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Comparator problem

i have a signal that has output levels of 0 and 5v ,i want to shift the levels to -5v for 0 and 5v for 5v so i used LM139 comparator but the output have some undesired oscillations although i use positive feedback,the input signal frequency is 100kHz and if i increase the frequency to 1Mhz the output signal is distorted ,i made the simulation using multism 7,so how can i overcome this problem?
thanks in advance
 

Re: Comparator problem

Try to look on the frequency response parameters of the comparator itself from the data sheet.

may be some coupling capacitors can remove this effect.
 

Re: Comparator problem

Look on the slew rate, bandwidth, noise, frequency response... of the LM139.

If the characteristics are useless for your application, try TLV3701, by TI ;-)

Regards,
Manu
 

Re: Comparator problem

try this[/img]
 

Re: Comparator problem

The circuit shown above contains an error. The inverting must be polarized with DC voltage but it is not. Comparator cannot work properly with only capacitor connected in series with its input.
 

Re: Comparator problem

kekon
you're right I screwed the pooch. I got the + and - reversed.
Pins 6 and 7 should be swapped for proper circuit operation.
also the formula for gain should be 1+(R2/R1)
Note to self never try to do a quick circuit.. duh!!
Thanks for catching it.
 

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