Configurable inductive proximity detector to detect ferrous or non-ferrous metal objects

An inductive proximity detector configurable to detect ferrous and non-ferrous objects, comprising:

• an oscillating circuit configured to generate a first signal at a frequency dependent on the proximity of a metal object to said oscillating circuit;
• an oscillator coupled to said oscillating circuit and configured to generate a second signal at a fixed oscillator frequency below a critical frequency of said oscillating circuit;
• a processing circuit configured to receive said first and second signals and to generate a detection signal;
• wherein said processing circuit comprises,
• a phase detector having a first input and a second input, said phase detector being configured to measure a phase difference between said first and second signals and to output a third signal based on said phase difference, said detection signal being based on said third signal;
• and
• an inverter device configured to provide,
• a first input configuration for said phase detector, wherein said first input of said phase detector receives a signal corresponding to said first signal and said second input of said phase detector receives a signal corresponding to said second signal, and
• a second input configuration for said phase detector, wherein said first input receives a signal corresponding to said second signal and said second input receives a signal corresponding to said first signal,
• whereby said processing circuit provides two phase detections, a first phase detection based on said first input configuration and a second phase detection based on said second input configuration, one of said two phase detections corresponding to a detection of ferrous objects and another one of said two phase detections corresponding to a detection of non-ferrous objects.