US Patent 7864051 Quasi-passive wakeup function to reduce power consumption of electronic devices

A quasi-passive wake-up function for an electronic device that employs a continuous low power standby mode compares a received signal to a predetermined signal and wakes up the device when the received signal is the same as the predetermined signal. An electronic device having a quasi-passive wakeup function includes a receiver for receiving at least one stimulus signal, a comparator for comparing the received signal to a predetermined signal, and at least one logic gate for waking up the electronic device when the received stimulus signal is the predetermined signal. In one application, identification tags are used to distinguish a unique tagged item from among a plurality of items with a similar appearance. When an interrogation signal is not present, the tags sleep at a very low power level.