US 12,380,309 B2
Radio frequency voltage limiter for an RFID transponder
Jorge Vicente De la Cruz Marin, Graz (AT); Lukas Zoescher, Graz (AT); and Slawomir Rafal Malinowski, Graz (AT)
Assigned to NXP B.V., Eindhoven (NL)
Filed by NXP B.V., Eindhoven (NL)
Filed on Nov. 17, 2023, as Appl. No. 18/512,188.
Prior Publication US 2025/0165739 A1, May 22, 2025
Int. Cl. G06K 19/06 (2006.01); G06K 19/07 (2006.01)
CPC G06K 19/0715 (2013.01) [G06K 19/0723 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A radio frequency (RF) voltage limiter for a radio frequency identification (RFID) transponder, the RF voltage limiter comprising:
an envelope detector having an input coupled to an antenna, the envelope detector configured to track an envelope of a signal received at the antenna, the envelope detector having an output for providing an envelope signal;
a peak detector having an input coupled to the output of the envelope detector, wherein the peak detector comprises a current mirror having an input coupled to the output of the envelope detector, and an output configured to provide a control signal;
a shunt circuit coupled to provide an impedance to the antenna in response to the control signal, wherein the impedance decreases with an increasing voltage magnitude of the control signal;
a first transistor having a first current electrode and a control electrode both coupled to receive a reference current, and a second current electrode coupled to the output of the envelope detector; and
a second transistor having a first current electrode, a control electrode coupled to the control electrode of the first transistor, and a second current electrode coupled to provide the control signal to the shunt circuit.