A 433 MHz 54 μW wake-up receiver that supports OOK/FSK/PSK demodulation schemes is proposed. Injection-locking and superregenerative reception provide the capabilities of demodulation and linear amplifications with superior sensitivity and high energy efficiency. For a data rate of 200 kbps and a BER < 0.1%, the proposed receiver achieves sensitivity of - 80/-78/-77 dBm under OOK/FSK/PSK schemes, respectively. Further, incorporating a loop antenna with a reception of an injection-locked oscillator, the receiver features a low-power mode of 11 μW with an energy efficiency of 55 pJ/bit. A prototype receiver is fabricated in a 0.18-μm CMOS process with an active area of 0.45 mm2.