A proximity sensor includes an active sensor, a passive target, and a measurement circuit. The active sensor includes an active resonant tank circuit that includes an excitation source, a first capacitor, and a first inductor. The passive target includes a passive resonant tank circuit that includes a second capacitor and a second inductor, where magnetic coupling between the first inductor and the second inductor varies as a function of physical displacement of the first inductor and the second inductor with respect to one another. The measurement circuit is configured to measure a coupled resonant frequency response in the active resonant tank circuit and provide a measured distance output based on the coupled resonant frequency response.