First integrated inductive proximity sensor with on-chip COMS readout circuit and electrodeposited 1 mm flat coil

摘要

The first fully integrated inductive proximity sensor has been relized with a 75 nH, 1 mm side gol electrodeposited squared coil and with on-chip l #mu# m CMOS readout circuit. The measured nomianl frequency contput is of 9 MHz and increases up to 11.6 MHz with an aluminum target placed at 50 #mu# m of the coil. The on-chip electronci interface is based on a differential relaxiation oscillator designed to be fast and to have a frequecy output increasw when approaching a conductive non-ferromagnetic target, thus enhancing strungly the sensor sensitivity. Furthermore a carful alyout design l eads to robustness towards the generated coil magnetic field.