I am designing rectifier for RFID tags. I need to calculate input impedance and input power.
I did PSS analysis and Transient analysis. Since my rectifier is non-linear circuit. I need to match it with antenna.
So, i need matching networks. I am using cadence software with UMC 180nm.
I calculated input impedance through many ways. i am getting different results. Now i am not clear which impedance is correct.
I need to calculate real part and img part of impedance then i could make matching network.
Some one told me to calculate impedance using DFT in cadence calculator. will it work?
can someone tell me the right way so that i could get correct values.
Hi Chandra
I'm not fully aware about how does Cadence work as I more familiar with ADS, but it should be very similar.
With ADS:
- I use a current probe to get the input current
- I perform a Harmonic Balance Analysis
- I extract Vin(1) and Iin(1) which are the input voltage and input current at the operating frequency (fundamental)
- I calculate Yin=Iin(1)/Vin(1)
- I calculate the equivalent shunt resistance by using the real part of Yin
- I calculate the equivalent shunt capacitor by using the imaginary part of Yin
See the attached document
Best Regards
Xavier
Hi Sir,
Thanks for your reply. I have already designed one RF rectifier using schottky diodes in ADS. I have performed LSSP and HB for getting the exact value of impedance and power levels.
However i calculated Zin=Vin(1)/Iin(1) (will it make any difference) instead of Yin.
This type of facility is not available in Cadence software (or i am not aware about this).
with regards,
Chandra Shekhar
Could you share your experience for calculating input and output power for nonlinear circuits?
I have used the following equation in ADS:
P_dBm =10*log(0.5*real(Vin[1]*conj(Iin)))+30
Chandra,
Were you able to run the simulations in Cadence? I have the same issue and questions and could not figure them out yet.
Rectifiers are non-linear circuits and the input impedance depends on the input power level. If you want to accurately simulate the reflection coefficient and the input impedance, I suggest using ADS and LSSP simulation. The LSSP also can be run in the new version of Cadence. You can refer to the following paper for more info.
Article A Dual-Mode RF Power Harvesting System With an On-Chip Coil ...
Hamed Rahmani sir, could you please help me with LSSP and HB in ADS for wideband impedance matching.
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