An Inductive 2-D Position Detection IC With 99.8% Accuracy for Automotive EMR Gear Control System

• Published in: IEEE transactions on very large scale integration (VLSI) systems 2017-05, Vol.25 (5), p.1731-1741
• Main Authors: SangYun Kim, Abbasizadeh, Hamed, Ali, Imran, Hongjin Kim, SungHun Cho, YoungGun Pu, Sang-Sun Yoo, Minjae Lee, Keum Cheol Hwang, Youngoo Yang, Kang-Yoon Lee
• Format: Article
• Language: English
• Subjects: Accuracy; Analog to digital conversion; Analog to digital converters; Automatic two-step impedance calibration; Automotive engineering; Calibration; CMOS; coil driver; Coiling; Coils; Gears; Impedance; inductive position sensor; Integrated circuits; Position measurement; Position sensing; Power consumption; Resonant frequency; Temperature compensation; time shared analog-to-digital converter (ADC); Transmitters; Vehicles
• ISSN: 1063-8210; 1557-9999
• DOI: 10.1109/TVLSI.2017.2651112

In this paper, the analog front end (AFE) for an inductive position sensor in an automotive electromagnetic resonance gear control applications is presented. To improve the position detection accuracy, a coil driver with an automatic two-step impedance calibration is proposed which, despite the load variation, provides the desired driving capability by controlling the main driver size. Also, a time shared analog-to-digital converter (ADC) is proposed to convert eight-phase signals while reducing the current consumption and area to 1/8 of the conventional structure. A relaxation oscillator with temperature compensation is proposed to generate a constant clock frequency in vehicle temperature conditions. This chip is fabricated using a 0.18-μm CMOS process and the die area is 2 mm × 1.5 mm. The power consumption of the AFE is 23.1 mW from the supply voltage of 3.3 V to drive one transmitter (Tx) coil and eight receiver (Rx) coils. The measured position detection accuracy is greater than 99.8 %. The measurement of the Tx shows a driving capability higher than 35 mA with respect to the load change.