M

#### M. Hamed

- Jan 1, 1970

- 0

This is either misleading or I am confused. Wouldn't that mean that if you have a cap connected in parallel with the secondary then that capacitive impedance will transform as is to the primary multiplied by some factor.

My analysis if correct shows that this is not the case. Resonance between the secondary inductance and the cap play a big role in the result. Am I missing something?

Case in point in the circuit here:

https://www.dropbox.com/s/t6vt868q3xwl8c7/Transformer with a Cap in the Secondary.asc

at 10 MHz a 2.5 nF cap is 6.8 Ohms if that was transformed by the turn ratio it would be .06 Ohm. Simulation shows that the voltage at the primary is actually 800mV with a 1 V supply, showing that the impedance is more like 200 Ohms.

This seems like a direct result of the 100nH inductor resonating with the 2..5n capacitor.

The load impedance didn't transform as dictated by the turns ratio!!