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Simple Queries but confused

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shaikss View Drop Down
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    Posted: 29 January 2012 at 5:59pm
I want to know the mechanism of power extraction of RFID UHF Tag.
I am aware that passive tags doesn't have its own power and they extract power and information from the reader (Transmitter).

Let the EIRP at Reader side is 4W and the transmitted power is restricted to 1W. Let the read range be 7~10m.

What is the amount of power received at the Tag antenna? It may be in the order of few uW to few mV.


Lets assume that it is in 10uW. This power is then fed to Tag chip. The tag chip powers up and the demodulator uses this power to extract the information.

What may be the open circuit voltage at the antenna terminals?

Assuming the rectifier to be 30% efficient, what will be the voltage level given to the subsequent stages?
How does a demodulator work with 10uW power as it has to power itself and extract info? 

Normally, a memory chip needs approx 2.7V. So, how many stages of rectifier/voltage multipliers/charge pumps are needed for a simple passive tags with minimum blocks/modules?

Please let me know the power budget analysis. I am unable to understand the power extraction and power consumption mechanism of diff blocks of RFID Tag.

Thanks in advance.

Rgds,
Shabana
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shaikss View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote shaikss Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2012 at 10:46pm
Amal,

Pls post here.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amal Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2012 at 10:49pm
Hi there Shaikss,

What you have asked for is along the lines of electrical engineering. This is beyond my knowledge. If you really need to know, I would look at UHF tag electrical specification documents to try and discern the information you're looking for.
Amal ;)

www.amal.net
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Post Options Post Options   Thanks (0) Thanks(0)   Quote shaikss Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2012 at 10:54pm
HI,

I have checked for UHF Tag specifications from Impinj manufacturers but I couldn't get answers to my Qs.
Felt that you might have done excessive research on the power domain too (Electrical Engg lines) and so posted my doubts here.

Can you please direct me to some design engineer from your list of contacts who can help me?
Sorry for troubling you but I don't have any clue/hint.

Thanks in advance.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amal Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2012 at 11:31pm
Hi Shaikss,

I've met the R&D guys over at Impinj... great guys. They are busy dudes, but the customer service people are usually very helpful (for customers). Do you have any Impinj gear that would qualify you as a customer?

I don't know anyone off the top of my head, but I'll put out a few emails directing some of my contacts to this post. It might take a few days for anyone interested to post a reply. In the mean time, try politely asking Impinj customer support if you could trouble them with a technical/design question... they might just oblige you. // if they do, please update this post! //

Other than that, I'm just as clueless on this one :)
Amal ;)

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Post Options Post Options   Thanks (0) Thanks(0)   Quote shaikss Quote  Post ReplyReply Direct Link To This Post Posted: 30 January 2012 at 11:59pm
Thanks Amal :)
I have raised a technical request at Impinj.
Once I get any reply, I will surely post it here.
Meanwhile, if you get any reply to this, pls post it.

Thanks!
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