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Smart Rotary Encoders

The rotary encoder detects the magnetic field of a permanent magnet attached to the end of the rotating shaft using CMOS magnetic sensors (MAGFET arrays) set in a square arrangement. The rotation angle is calculated in real time by logic circuits integrated with the sensor arrays. Using a fine-pitched sensor array and a digital domain signal processing technique, a compact encoder with high resolution can be realized. A prototype sensor chip with dimensions of 4.3 x 4.3 mm2 is implemented. The CMOS rotary encoder can achieve the resolution of 10 bits per rotation.

Block diagram of sensor chip Arrangement of sensor chip and permanent magnet
Prototype Sensor chip


  1. Kazuhiro Nakano, Toru Takahashi and Shoji Kawahito, "A CMOS Smart Rotary Encoder Using Magnetic Sensor Arrays," IEEE SENSORS 2003, pp. 206-209, 2003.

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