What is real GND in wireless powered system?

Dear all,
In wireless powered system, like RFID tag, IC is powered by
the power capture from antenna. That means only the two antenna
terminals are interface between IC about outside world.
My question is, what is whole chip GND of such kind of chip?
One of the antenna terminal? or some other thing?

Best wishes
fxxjssc

I think all the RF chips should be a VDD and GND pin.
And sometime there are many VDD and GND for different block.
Especially for SOC, because there are RF, analog and Digtal circuit.
So there will many GND pins in the chip.

Dear jeckhale,
Only two pins present in RFID tag IC and
such application is ultra low power, so no need
for more power and gnd pins.

Thanks

Some manufacturers show a bridge rectifier in RFID chip block diagram, some don't give any details. Also equivalent circuits used for test purposes usually have a bridge rectifier. The main differences resulting from this circuit details are regarding the load modulator design.