In this paper, a low-power crystal-less event-driven receiver that is suitable for biomedical implants is presented. The design is intended to be embedded into a smart stent, or can be used for other miniaturized biomedical implants as well as other size-constrained and low-power applications such as Internet of Things (IoT). In order to facilitate operation using harvested energy, the receiver operates from a low supply voltage of 0.5 V. The system uses an envelope detector with programmable scaling factor to provide a better trade-off between sensitivity and power consumption. A proof-of-concept receiver with two gain settings is designed and fabricated in a 0.13-μm CMOS process. The monolithic system does not require any external components, occupies a chip area of 0.208 mm ² , and consumes 32 μW while achieving sensitivity of -50 and -53 dBm for the two different scaling factors.