Rfid system that includes a hybrid rfid tag

A method of operation of a hybrid radio-frequency identification (RFID) tag, the method comprising:

• receiving, from an RFID reader, a first radio-frequency (RF) signal;
• executing a first mode of operation based on receiving the first RF signal, the first mode of operation comprising:
• harvesting the first RF signal to produce a direct current (DC) voltage;
• providing power to a first component of the hybrid RFID tag based on the DC voltage;
• coupling the DC voltage to a capacitor through a first charging circuit that supports charging of the capacitor at a first charging rate, the first charging rate selected to prevent the DC voltage from dropping below a threshold voltage level over a first period of time;
• executing, by the first component, during the first period of time, a demodulation operation upon the first RF signal;
• and
• terminating coupling of the DC voltage to the capacitor through the first charging circuit when a first amount of charge accumulated in the capacitor exceeds a threshold charge level;
• coupling the DC voltage to the capacitor through a second charging circuit that supports charging of the capacitor at a second charging rate that is faster than the first charging rate;
• and
• terminating the first mode of operation when the RF signal is no longer received by the hybrid RFID tag.

A hybrid radio-frequency identification (RFID) tag comprising:

• a radio-frequency (RF) front-end circuit configured to receive a first RF signal from an RFID reader;
• an energy harvester circuit coupled to the RF front-end circuit, the energy harvester circuit configured to produce a direct current (DC) voltage by harvesting the first RF signal;
• a tag controller that is powered by the DC voltage produced by the energy harvester circuit;
• a charge storage circuit comprising:
• a capacitor for storing a charge based on the DC voltage;
• a current-controlled switch that operates to provide a first level of current conduction into the capacitor in response to a first control signal provided by the tag controller to the current-controlled switch;
• and
• a bi-directional switch that operates to provide a second level of current conduction into the capacitor in response to a second control signal provided by the tag controller to the bi-directional switch.