Circuit for a passive radio identification tag operating in a UHF band and method for operating a circuit

A circuit for a passive radio-identification tag operating in a UHF band, configured for radio communication with a reader which sends a periodic read signal,

• wherein a period of the read signal comprises an energy recovery phase and a communication phase,
• the circuit comprising:
• a control device configured to accumulate an energy reserve from the radio wave during the energy recovery phase and to communicate with the reader during the communication phase,
• an interface to connect an external analogue sensor, the interface comprising:
• an electrical connection configured to connect and supply the external analogue sensor with electricity and to acquire the analogue measurement from the sensor,
• an amplifier configured to amplify the signal of the analogue measurement from the sensor, and
• an analogue-digital converter configured to digitize the amplified analogue measurement from the sensor, wherein the energy recovery phase comprises an acquisition phase during which the interface supplies the external analogue sensor, acquires, amplifies and digitizes the measurement from the sensor,
• wherein the control device is also configured to:
• supply the interface to acquire the amplified and digitized measurement during the acquisition phase, and
• transfer the amplified and digitized measurement to the reader during the communication phase of the same period.