Maker Pro
Maker Pro

RF power harvesting

ahmed

Nov 26, 2010
3
Joined
Nov 26, 2010
Messages
3
Hello there,
This is my first thread on this site so excuse me if it were not the correct section to discuss what i am going to ask for, anyway, i have the following problem:
I am asked to design a RF power harvesting circuit on PCB board to provide a 1.8v supply with current capability up to 1mA, ripples should be as low as possible but no obvious constraint here, the settling time should be as minimum as possible,
The input is an RF signal with 13.56MHz and peak to peak voltage less than 10mv, the whole circuit is simply as following: coil antenna->matching circuit->voltage multiplier->LDO
later i should include a backscattering block to transmit binary data to the reader

Allright, this was a general desription to make everything clear, now i have few questions:
1-which is the best tool to use (the tool should perform both simulations and PCB layout)? i already have altium desiger but i want to make sure if there was any better tool
2-I need a discrete 4-terminal mosfet with low threshold, low parasitics, low on resistance and high current capability, actually this is my biggest problem, i don't have any idea where or how to search for one with these requirement, so any help there would be appreciated
3-After step 2 (choosing the Tr) i need to find a simulation model, the model should be pspice with any level available, but my question here is there anyway to find simulation models for cadence (virtuoso) ?
4-What is the difference between LDO and normal regulators ?

Finally, if you have any useful information related to the project i would be very grateful if you informed me

Thanks in advance
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
Does your input signal provide a current in excess of about 200 mA?

Because that's what you'd need for the input power to exceed the output power that you want (and that is a requirement).

The only realistic way is to step the voltage up with a transformer first, before rectifying the AC. You would need to use high speed diodes for that, and preferably not a bridge rectifier as that would be far too inefficient.

When you say "4 terminal mosfet" do you want a dual gate mosfet, or one with an external substrate connection?
 
Last edited:

ahmed

Nov 26, 2010
3
Joined
Nov 26, 2010
Messages
3
@steve
1-allright, first relax the condition on the input/output power to be 1mw (2v,500uA) , the input has the same power (50mv,20mA), however i can not use a transformer at all, there is a simple reason behind that, my teacher expects me to go for ASIC implementation if the PCB board were ok, the same reason applies for the use of diodes, i am only allowed to use mosfets (0.13u technology to be specific should be used in ASIC)
2-I meant external substrate connection, MIC94030 seems to work at higher voltages than available to me, i need a mosfet with much lower operating voltages, typically in the range of 10mv~100mv

Excuse me if it seems i am not professional because i am really are :) ,actually i am still learning and this a whole new area to me from the very begining to the end
 
Last edited:

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
OK, I have no experience with 50mV power rails. I suspect you would be looking at some form of switched capacitor voltage multiplier with synchronous rectification of the input signal, but I have no idea how you're going to do that with such a small signal.

I suspect it's the sort of thing that is done in RFID tags though.
 

ahmed

Nov 26, 2010
3
Joined
Nov 26, 2010
Messages
3
yes, that's right, it is exactly a passive RFID tag, ummm ok forget about this, as i said before i already have some schematics but the main problem is the mosfets and their models, i did my best trying to find an appropriate one but no results, so at least can you help me to find a suitable mosfet for this application, then i will try to find the model myself ? this would be great, or just tell me where to look for something like this? a discrete mosfet with body terminal and some specs (low parasitics, high transconductance, ..), there must be some sites doing this kind of things, right?
Thanks for your concern
 
Last edited:
Top