Proximity sensor with health monitoring

A proximity sensor includes a relatively simple health monitoring circuit. The proximity sensor includes a variable gain oscillator, a feedback circuit, and a proximity determination circuit. The variable gain oscillator has a gain that varies with the proximity of a target to a sensor coil, generates an oscillating electrical signal having a substantially constant amplitude magnitude, and generates an energy signal representative of the electrical energy needed to sustain oscillations. The feedback circuit supplies feedback to the oscillator, and the proximity determination circuit, based on the energy signal, supplies a proximity signal representative of target proximity to the sensor coil. The health monitor circuit also receives the oscillating electrical signal and supplies a health status signal representative of proximity sensor health.