Discussion in 'Homework Help' started by Pheezy, Sep 10, 2014.

1. ### Pheezy Thread Starter New Member

May 16, 2014
11
0
Hey all,

I intend to calculate the impedance as indicated but I am unsure on how I would do this. The reason I need to calculate this impedance is because this is part of a bigger project where I am trying to match the source impedance with the load impedance and I will need to design a impedance matching circuit for it.

The source is a 50 ohm antenna and this connects directly to this circuit in the given image.

NOTE: The diodes are the BAT46WJ schottky diodes. Essentially its a rectifier with multiple stages.

Any help would be appreciated.

Cheers

2. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,066
The input impedance of this voltage multiplier circuit is greatly influenced by what sort of load is connected across the DC out terminals....

3. ### Pheezy Thread Starter New Member

May 16, 2014
11
0
Hey Mike,

In regards to the load, lets assume its 1000 ohms. I still don't know how I would calculate the impedance though.

4. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,066
What are the capacitance values? What frequency?

5. ### Pheezy Thread Starter New Member

May 16, 2014
11
0
2.4 GHz frequency is the source AC signal and capacitance values haven't been decided yet but perhaps in the nF range.

6. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,402
1,223
How much power are you anticipating you will "harvest"?

What is the power or the "source"?

7. ### Pheezy Thread Starter New Member

May 16, 2014
11
0
@JoeJester Not anticipating much power. This is all just a simulation. Not planning to put in less than +10 dBm. The voltage in will be enough to switch the diodes on (BAT46WJ have low turn on voltage).

Apr 26, 2005
3,402
1,223
9. ### vk6zgo Active Member

Jul 21, 2012
677
85
That circuit is OK at Mains & Audio frequencies,but as you increase in frequency,the diodes will start to appear to have capacitors in parallel with them,the capacitors will look like inductors etc.
And that is just at HF!
At 2.4GHz,the circuit will again look completely different.

I wish you good luck.

10. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,402
1,223
Have you done the simulation yet?