Class E RF Power Amplifier 13.56MHz

[sukhmani]

After reading few documents about efficient power amplifiers, Class-E amplifier seems to suit the application that I need. So I have designed a circuit using MLX90130 to match with 50 ohm antenna which gives a power of 300mW. For the application, I require 2W, hence the need for power amplifier.

I have tried 2 variations :
One is not to include the shunt capacitance at the drain of IRF110 FET and at the load for harmonic suppression.
Other is to include both of them.

Also I came across one document where Class E RF Power Amplifier is simulated for 2W power at 13.56MHz for 50 ohm. But using those values too, I do not get 2W of power. This is the link to the circuit.
https://www.elektroniknet.de/automation/sonstiges/artikel/28383/3/

I am connecting the symmetric output after balun to the gate of this PA circuit. 50 ohm load should I use a resistor or just the SMA conctor and coax?
It would be grateful if I get some information about some moificatios I could make in the above circuit.

Thank you

 

[FvM]

Please consider that RFID reader operation depends on load modulation, which involves the ability to read the RX signal while an unmodulated carrier is transmitted. Connecting external PAs between reader IC and "antenna" coil is possible under some restrictions, but must not disturb the RX operation.

Don't know what you want to achieve, regular wide range operation like ISO15693 or some kind of range extension for proximity card snooping?

 

[sukhmani]

I would like to use the PA for ISO15693 for transmitting information to the tag. How can I achieve the non disturbance at the Rx signal?

Thank you

 

[FvM]

I don't know in detail. Clearly the differential RX inputs must be able to pick up the signal from antenna coil. And the specified voltage range has to be kept. There might be additional Melexis application notes for PA connection in 15693 applications.

Referring to your previous question, the PA input must not necessarily be connected through a balun, it could also use a single ended TX output, I think. In this case, the load impedance should be not too low.