Paul__B:
SkiBum326:
Correct me if I'm wrong,Oh, he will!
Ah you know me so well.
You can not get a power increase from a transformer because that would break the conservation of energy principle and allow things like a perpetual motion machine. The second law of thermodynamics has something to say about it as well.
There are three main causes of losses in a transformer.
- I2R losses - Heating of the coil caused by resistance in primary and secondary windings.
- Dielectric losses due to the coil's core material.
- Coupling loss due to the fact that the windings will not share all the magnetic field.
That is quite a good chip for a simple RFID reader but it is never going to win any prizes for range.
It has a PLL that is constantly twiddling with the excitation frequency to keep the coil in resonance. This means that while the antenna is in resonance the token is not being driven at its resonant frequency. You can adjust the coil or capacitor so that the twiddled excitation frequency is closer to the excitation frequency of your token. The token excitation is different in different tokens but normally has a certain range, which is less than this system can span. This will improve the range.
However, this chip can also have it's range improved, it says in the data sheet:-
Read sensitivity (and thus reading range) can be increased by using external envelope detector circuit. Input is taken on antenna high voltage side output is directly fed to CDEC_IN pin.
But for ultimate range throw that chip away and make a reader from it's discreet bits. The maximum range is not achieved at the resonate frequency but just at one side or other of this.