The article introduces an antenna-envelope detector (ED) co-designed wake-up receiver (WuRX) that can automatically detect the frequency-hopping sequence from 840 to 970 MHz. Prototyped in 65nm CMOS, the WuRX supports three modes: 1) low-power mode that achieves -68 dBm sensitivity with 9.9nW power consumption, 2) Q-enhanced mode that provides 22 dB rejection to an on-off-keying (OOK) modulated pseudo-random-bit-sequence blocker at 10 MHz offset and 41 dB rejection to a continuous-wave one at 10 MHz offset, with a power consumption of 39.6 μ W and 3) 2-stage wake-up mode that combines the advantages of both the low-power mode and Q-enhanced mode, with a power consumption of 33.7 nW. These characteristics are achieved by exploiting 1) an antenna-ED interface where the Q-factor of the antenna is equal to the Q-factor of the capacitor to ensure a conjugate matching condition for the maximum available power transfer from the antenna to the ED, 2) a frequency tuner connected to the antenna-ED interface calibrated by a frequency-locked loop, and 3) a Q-booster reconfigured from the frequency tuner for boosting the passive gain and narrowing the bandwidth of the interface.