Patent ID: 7952323

Claim:
An integrated radiofrequency circuit integrated in a substrate, wherein the circuit includes: (a) an antenna that receives radiofrequency signals; (b) a rechargeable battery; and (c) a battery charger using said radiofrequency signals received by the antenna to charge said battery; wherein said battery charger is integrated in the same substrate as said integrated radiofrequency circuit, and wherein said battery charger includes i. calibrating means; ii. a current source calibrated by said calibrating means and delivering a charge current of constant maximum intensity drawn from the received radiofrequency signals; and iii. a first comparator between a reference quantity representative of an end of battery charge level and a variable quantity representative of the battery charge level supplying at output a control signal ordering the battery to be charged or not charged, wherein said first comparator is a voltage comparator between a reference voltage and a battery voltage, wherein said first comparator includes linearization means for converting the reference voltage into said reference quantity representative of the end of battery charge level and for converting the battery voltage into said variable quantity representative of the battery charge level.