Real time problem

[Alfred873322]

Halo, recently im doing project and urgently need to solve the problem.

im designing RF energy harvesting circuit, where the circuit will convert the RF to be electricity and store in capacitor. And of course the output of the circuit is DC voltage. The circuit already been tested in Multisim 10.1 and also in real circuit.

However, the accumulate voltage at output from real circuit and simulator is totally different.

Take an example, i will pump in 100MHz, 20dBm from signal generator to the circuit. After 30 second, the accumulate voltage is 15.06V

However, the result was totally different in simulator. Function generator been used and 100MHz, amplitude 3.162Vp, offset 1V been set. The accumulative voltage only 1.117V  after 30 second.

Same case happen to other frequency and amplitude as well.

The circuit and input is totally same for simulator and real circuit, but why then output was different?
It's multisim 10.1 unable to support real time or product option problem (student, educator, professional) 

[_user32]

Alfred873322,

Can you give us some idea what is connected between the generator and the output - obviously it is some AC to DC converter; but is it some type of transformer based circuit - basically what is the mechanism of the charge pump?

The reason I am asking is that you may be using some ideal devices for your circuit simulation (ideal Transformer, RLC parts) and at higher frequencies the ideal models may not be taking into account losses that may severly limit the performance of these components at the 100Mhz frequency.   For instance a capacitor at DC may act completely differently (like a more complex RLC model) at higher frequencies.

Regards,

Pat Noonan

National Instruments

[Alfred873322]

Actually, the Voltagedoubler circuit is connected in between the signal input from signal generatorand output to the supercapacitor. 

You might refer the circuit from thiswebsite: http://etd.library.pitt.edu/ETD/available/etd-07212004-192328/unrestricted/Harrist_Thesis_072804.pdf,page 23 (Figure 4.3: Voltage Doubler with Output Capacitor).

The functions ofthe circuit was to convert the AC to DC as well as increase the voltage level. 

As what i have did, the input was from signal generator(RF), frequency tested from 100MHz to 2.4GHz, 100MHz apart. Diod usedwere Schottky diod 1N5711, PET film capacitor (0.02µF), Cout is my supercapacitor (2.2µF) which was used tostore the electric energy after harvested.

As i mention before, the voltage value from simulator andreal circuit was totally different even the input signal and circuit from bothwere same. Need your help, please. Anyway, thank you.