Home: Message List - How to pull up a voltage?

Re: How to pull up a voltage?

communitymanager@premierfarnell.com — Mon, 15 Mar 2010 08:42:02 GMT

oops, got the diode the wrong way round (would get a negative result). see new attached.

Re: How to pull up a voltage?

communitymanager@premierfarnell.com — Mon, 15 Mar 2010 03:25:44 GMT

Hi Ghamble,

Thanks for the info.

Re: How to pull up a voltage?

communitymanager@premierfarnell.com — Fri, 12 Mar 2010 11:32:09 GMT

How about a simple circuit that is used in video, it is called a DC restorer. It will take the 1volt peak to peak signal and give a nought to 2 volt output.

Re: How to pull up a voltage?

communitymanager@premierfarnell.com — Wed, 10 Mar 2010 08:54:46 GMT

Hi Koh,

There's is plenty of information on the internet etc and the basic circuit I posted show the essential components / theory.

A bias-T is a three port network with signal in, signal out and a DC offset input. The input has a capacitor on it for DC blocking, the DC source is fed in via an inductor to block RF and the whole thing allows the incoming signal to be superimposed if you like on a DC source.

Re: How to pull up a voltage?

kevinkhua@gmail.com — Wed, 10 Mar 2010 08:11:48 GMT

Hi Guys,

Have received customer's reply, apparently he has registered with E14 and saw all the responses for this discussion.

Below is his reply:

"Kind of surprise to see so much information generated. The source is actually an AWG, Arbitrary Waveform Generator. It's a very high frequency signal (a pure sin or square wave), in terms of GHz (Up to 6GHz) and definitely a Bias-T is able to do the job as there is active component inside. Ghamble understands and interprets them correctly. I was just thinking whether there is any cheaper components hence posting a question. Nevertheless, I'd stick with a Bias-T. Thanks for your support! =)"

Hey Ghamble, you have hit the jackpot. Thanks!

Once again, I would like to thank everyone for all the inputs. Customer is amazed with the responses generated from E14 and certainly will be the top of his list when he need any support/info in future.

Cheers

Kevin

Re: How to pull up a voltage?

communitymanager@premierfarnell.com — Wed, 10 Mar 2010 07:56:39 GMT

Hi Gamble,

Would like to know a little more about bias-T, how does it works?

Please advise. Thanks.

Re: How to pull up a voltage?

kevinkhua@gmail.com — Wed, 10 Mar 2010 06:45:29 GMT

Hi Guys,

Thanks for the input. I'm still waiting for customer inputs for more information. Will update you guys asap.

Regards

Kevin

Re: How to pull up a voltage?

communitymanager@premierfarnell.com — Tue, 09 Mar 2010 22:38:12 GMT

I was thinking along the lines of this. This is a sort of "GCSE level" answer.

Re: How to pull up a voltage?

communitymanager@premierfarnell.com — Tue, 09 Mar 2010 19:38:58 GMT

Depends on what you thinks going on here, Kevin didn't give a lot of info, but if you know what an SMA connector is, then you might take an educated guess that the -1V to 1V signal is probably some kind of 100s of MHz to GHz signal going to say an Antenna. If you think this is what might be going on, (and that's my guess, not a fact) then I don't think a switching regulator makes a lot of sense. I can't think of a single instance of ever seeing a switching regulator used in an R.F. signal path, it's not a natural place to find a DC to DC converter.

But this is all just guess work as to the end application and could be completely wrong, I was just trying to help Kevin out and based on some of the technologies he's mentioned my guess is this is a Radio Frequency signal path which for some reason needs a D.C. Bias applied to the signal, if that's the case, then I'd at least start by looking at a bias-T.

If memory serves, the below should be a basic circuit for a Bias-T

Re: How to pull up a voltage?

communitymanager@premierfarnell.com — Tue, 09 Mar 2010 19:29:08 GMT

Not sure how you propose to use a potential divider circuit to add a 1V bias. Either your missing something or I am