Wireless sensor nodes require an ultra-low power RF transceiver in order to meet the stringent power requirements of the system. Since the transceiver consumes power whenever it is active, it would be advantageous to leave the receiver off and wake it up only when data is being received. This sort of architecture is termed a reactive radio, where the node remains in standby mode and only reacts when data is sent to the node. With this goal in mind, this research explores a minimum power RF receiver that would detect a wakeup signal and turn on the node's main RF transceiver for data transfer.