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Rectenna simulation for Rf energy harvesting on ADS (Read 469 times)
Asma.Didi
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Rectenna simulation for Rf energy harvesting on ADS
Mar 08th, 2018, 6:45am
 
i am making an Rf energy harvesting circuit using ADS working on 3 bands 1.8GHZ , 2.1GHZ and 2.4 GHZ and i m getting the Vout very low around 0.002v and i m getting this message during the simulation and i couldnt know whats the problem i have or what i need to add or check can you
help me please
##Warning detected by hpeesofsim during DC analysis `HB1'.
Matrix is singular (detected at node or branch `L2.i').
Warning detected by hpeesofsim during DC analysis `HB1'.
Circuit converged after a virtual resistance of 1 TOhms
was added between each node and ground, and a virtual
resistance of 1 pOhms was inserted in each current branch.
Possible causes include floating nodes or missing ground.
Warning detected by hpeesofsim during HB analysis `HB1'.
More than one mixing term has landed on frequency 300 MHz.
Warning detected by hpeesofsim during HB analysis `HB1'.
More than one mixing term has landed on frequency 2.1 GHz.
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Murat H. Eskiyerli
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Re: Rectenna simulation for Rf energy harvesting on ADS
Reply #1 - May 6th, 2018, 5:49am
 
Dear Asma,

You cannot simulate RF-DC rectifiers using Harmonic balance. Harmonic balance assumes that the circuit is oscillating around a bias point. In a rectifier, this is certainly not the case.

I would suggest that you should go through the presentation I made in 2016 IEEE RFID conference about the simulation and design of RF-DC rectifier circuits using circuit simulators. In summary, you need to use either transient or Shooting-Newton type analyses.

http://www.revsemi.com/files/documents/ieeerfid2016.pdf

Murat Eskiyerli
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Murat H. Eskiyerli, Ph.D.
Revolution Semiconductor Labs
http://www.revsemi.com
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Ken Kundert
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Re: Rectenna simulation for Rf energy harvesting on ADS
Reply #2 - May 6th, 2018, 9:33am
 
Conceptually both Harmonic Balance (HB) and Shooting Methods (SM) only require the existence of a steady-state solution, and this circuit would have a steady-state solution. So there is no reason why HB would not work on this circuit. Having said that, there are differences in the ability of HB and SM to converge on strongly nonlinear circuits. In general HB will have more trouble than SM.  However, you are not having convergence problems. The error messages you are seeing are all innocuous.

One thing you should assure before you go too far is that your circuit actually works as you expected. One reason why you are seeing a low voltage is simply because that is the voltage your circuit would produce. Transient analysis could be a good sanity check.

One possible reason why HB would not give accurate results is because you did not specify enough harmonics to be solved for. The temptation for this is great. Intuition generally leads you to specify too few harmonics, and if you increase the number of harmonics the simulation becomes very expensive. Particularly with a three tone simulation.  You might try reducing the number of tones and increasing the number of harmonics.

-Ken
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Murat H. Eskiyerli
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Re: Rectenna simulation for Rf energy harvesting on ADS
Reply #3 - May 6th, 2018, 10:52am
 
Dear Ken,

You might be right about HB should converge.  It indeed does but you would not see your output cap charged to any meaningful value.   I possibly could not answer with any degree of certainty about the causes. I worked quite a bit on them back in 2013 to 2015, but could not get Hspice-RF HB analysis to yield meaningful results.
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Murat H. Eskiyerli, Ph.D.
Revolution Semiconductor Labs
http://www.revsemi.com
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