This letter describes a low-energy wake-up radio that is based on passive down conversion. The receiver activates when it receives two closely located frequencies that are down converted in the passive mixer. The down converted signal is applied to a low-frequency wake-up IC that provides an identification code and wakes up an active radio for further communication. This letter derives an expression for the voltage sensitivity of the mixer and verifies the concept experimentally at 2.45 GHz. The wake-up radio consumes 6.8 µA at 3 V.
- wake-up radios
- wireless sensors