maximum available resistor value in the market

[Junus2012]

hello

I am constructing a measurement setup for simulating OTA. the simulated output impedance is 50 M Ohm, thus in order to characterise my circuit without degrading the voltage gain of the OTA, then need a resistor should be at leastof 10 * 50 M Ohm = 500 M ohm or greater.l

I dont know if such a great single resistor is available or not , or what is the maximum available resistor so I could connect the extra in parallel.

Thank you very mucch

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Note: the resistor I need is low power resistor

 

[kripacharya]

what is the precision that you need for this resistor ? 5% ? 1% ?

Note that even a normal PCB on FR4 material will have less resistance than this....

 

[Junus2012]

any one of them or even more, no problem for me

Thank you very much

what is the precision that you need for this resistor ? 5% ? 1% ?

Note that even a normal PCB on FR4 material will have less resistance than this....

 

[erikl]

... resistor should be at least of 10 * 50 M Ohm = 500 M ohm or greater.

What about a sub-threshold 1nA constant-current (CC) source? Its resistance is high enough - and can easily be calculated.

 

[tpetar]

Check this :

1206 50MΩ
https://uk.farnell.com/vishay-techno/crhv1206af50m0fkft/resistor-50mr-1206-hi-v/dp/1572806RL

Datasheet
https://www.farnell.com/datasheets/1640465.pdf

Check in datasheet there is greater resistors.

 

[Junus2012]

Erikl, from the principle of load, this is possible and a new thing for me to know, however, normal resistors help me more because if for example I would test the OTA in the inverting setup, with resistor I can control the gain (R2/R1) but with the current supply I cant

Thank you

What about a sub-threshold 1nA constant-current (CC) source? Its resistance is high enough - and can easily be calculated.

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Oh my ***

CRHV2512 is 50 G Ohm, Wow

but please it is written in the data sheet range from 12 M to 50 M ohm, what means of a range in a constant resistor ???

Check this :

1206 50MΩ
https://uk.farnell.com/vishay-techno/crhv1206af50m0fkft/resistor-50mr-1206-hi-v/dp/1572806RL

Datasheet
https://www.farnell.com/datasheets/1640465.pdf

Check in datasheet there is greater resistors.

 

[erikl]

I am constructing a measurement setup for simulating OTA. the simulated output impedance is 50 M Ohm, thus in order to characterise my circuit without degrading the voltage gain of the OTA, then need a resistor should be at leastof 10 * 50 M Ohm = 500 M ohm or greater.

If you just need a measurement by simulation, you don't need a real resistor device, you can use any virtual resistor from your analog lib.

 

[Junus2012]

;-) of course i will do this if i am simulating, but want it for real measurement setup

Thank you any way

If you just need a measurement by simulation, you don't need a real resistor device, you can use any virtual resistor from your analog lib.

 

[BradtheRad]

Several websites are run by electronics hobbyists and engineers, where you can purchase components from a list of a few items. I once purchased 50 Meg and 100 Meg resistors from such a website.

Similar parts are available on Ebay.
This link does a search on '(50, 100, 200, 500) meg ohm resistor'.

 

[tpetar]

Oh my ***

CRHV2512 is 50 G Ohm, Wow

but please it is written in the data sheet range from 12 M to 50 M ohm, what means of a range in a constant resistor ???

Ranges are linked with particular resistor manufacturing serie. They make fixed value from that range for that resistor serie.

 

[Junus2012]

Thank you,

Do I need to request them or it is available in all the values in the range ?

Ranges are linked with particular resistor manufacturing serie. They make fixed value from that range for that resistor serie.

 

[tpetar]

They have many values, not all, but many. Its good to see detailed catalog or ask them for specific value.

 

[Junus2012]

Thank you very much

 

[FvM]

Referring to the original question, I don't think that you actually need a high-ohmic resistor to determine your OTA parameters. I presume there are several more intelligent methods.

 

[Junus2012]

Hello FvM

it is easy to construct the PCB un-expensive setup with the resistors, however I am also interest to know these method you want to tell, please

Referring to the original question, I don't think that you actually need a high-ohmic resistor to determine your OTA parameters. I presume there are several more intelligent methods.

 

[erikl]

Erikl ... however, normal resistors help me more because if for example I would test the OTA in the inverting setup, with resistor I can control the gain (R2/R1)

Of course. We used Victoreen glassed resistors, about a hundred years ago. Now the company doesn't exist any more :-(

CRHV2512 is 50 G Ohm, Wow

But here you can still buy them, up to 450MΩ, and cheaper than those offered @ eBay.

We had to mount them on teflon bearings and wash them with alcohol to keep their high resistance ...

 

[Junus2012]

Thanks a lot Erikl

Of course. We used Victoreen glassed resistors, about a hundred years ago. Now the company doesn't exist any more :-(


But here you can still buy them, up to 450MΩ, and cheaper than those offered @ eBay.

We had to mount them on teflon bearings and wash them with alcohol to keep their high resistance ...