i want to calculate the diode HSMS-8101 input impedance to be 22-j20 for 1000 ohm load and 50 ohm source and 10 mW input power using ADS listed in the reference paper is (A compact and wideband circularly polarized rectenna with high efficiency at x-band).
or the methods used in ADS to calculate the diode impedance.
Hi,
You should create an accurate model of the diode using the manufacturer's datasheet. You could then simulate the large signal S-parameters of the diode using ADS.
Please see the attached application note 1156 from Agilent
Hope it helps.
i am new in ADS simulator and here is my simulation shown in attached figure
please can you guide me in calculating its impedance correctly.
you are right Remi Cornwall, but this diode will be a part of total rectenna system which should be accurately modeled using ADS to be correctly matched in the circuit. so i asked for help in ADS design.
The calculation what you are talking may be static. The diode under discussion has a linearity in the range of DC bias of upto about 0.2 V DC and in terms of RF power, it has a range of -10dBm to +10 dBm. As a caution of word is, calculated value will be useful only in specific condition.
Also its impedance is varying with temperature. In case of variable environmental situation, it will have different behavior
I know, this is not an answer of your basic question but I am conveying a word of caution, while analysis
Your simulation as it is set up now is measuring S-parameters at the output. You have to redefine the simulation as a harmonic balance analysis. Here are my recommendations:
1. Replace the S-param port term2 with a Resistor with value 1000ohms.
2. Replace the S-param analysis with a Harmonic Balance analysis.
3. Name the node at the input to V1. Harmonic Balance will solve harmonic voltages this node.
4. Add a current probe at the input in series. Harmonic Balance will solve for harmonic currents from this probe.
5. Run the simulation, and in the data display, write an equation for Zin = V1/Iprobe.I
6. From Zin, you can extract the impedances. Zin at DC will be Zin[0], at fundamental freq=Zin[1], second harmonic Zin[2] and so on. Manually changing the input freq & power, you should see Zin vary as a function of input power & freq.
7. If your Zin result does not vary as a function of input power, it is likely your diode model is a linear model.
8. You can further refine the simulation by letting the simulator sweep the input across frequency and power levels. However the setup & extraction of Zin in for this case is rather complicated and long to explain here.
Another thing to note, at 10GHz, in my experience, it is quite difficult to find an good model. You need to check if the diode model is valid at 10GHz. An also, your load, may not be 1000 ohms at 10GHz, it will likely be some complex impedance.
I include some links to assist your understanding of harmonic balance simulation in ADS.
https://www.utdallas.edu/~rmh072000/Site/Software_and_Links_files/7B_lab.pdf
http://www.ece.ucsb.edu/~long/ece145a/ADS_Harmonic_Balance.pdf
Be careful when doing this, the input impedance of the rectifier is input power dependant. A small signal simulation won't give you much. You need to do a harmonic balance and look at the voltage and current at the input of the rectifier, then work backwards to determine the input impedance. Chances are, you will only achieve a good match over a small range of input powers.
Dear Collage
thank you for your help. i tried all your steps and modeled the diode. but the input impedance is incorrect. the paper states that its input impedance is 22-j55 at 5.8 GHz while my simulation gives 1000-j47.6
i attached a photo for the program and the program. can you look at it and see if i missed any thing.
Your simulation is correct., but you need to put a capacitor in parallel with the 1k resistor. This will smooth out the peaks. 100pF or 1nF should be fine. It will be a virtual short at 5.8 GHz, so your input impedance will drop a lot.
Looking from input side, diode and R1 (1000 Ohms) are in series and diode has low resistive value (of the order of 22 Ohms), hence looking from input side, 1000 Ohms will predominate. Mr Gavin T Watkins has rightly suggested the idea of strapping
Make the complete circuit and perform the large signal s parameter (LSSP) simulation in ADS. LSSP is good for nonlinear response of rectifier. It also offers the flexibility to change the input power. So you can gave the different values of input impedance for different input power levels.
how to calculate input impedance of a bridge rectifier in ADS?
I want to match the impedance of antenna & rectifier.
Plz help me
Diode Matching Circuit http://web.ecs.baylor.edu/faculty/baylis/eel4421/EEL4421_6935SoftwareLaboratory5Fall2007.pdf
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