CMOS magnetic field to frequency converter

In this paper, a CMOS magnetic field to frequency converter with high resolution is presented. It is composed of two voltage-controlled ring oscillators whose output frequency differences linearly vary with the magnetic field perpendicular to the chip surface. The prototype circuit has been fabricated in a 0.5-/spl mu/m CMOS process and operated at a 5-V supply voltage. The measured sensitivity is 24 kHz/mT and the power consumption is 5.1 mW. The small equivalent resolution of at least 20 /spl mu/T can be achieved. The frequency offset is 42 kHz when no magnetic field applied. Its nonlinearity within /spl plusmn/120 mT is smaller than 0.56%.

[1]  J. Ryan,et al.  Magnetic field sensitive amplifier with temperature compensation , 1992, 1992 IEEE International Solid-State Circuits Conference Digest of Technical Papers.

[2]  S. Gumenjuk,et al.  Advanced integrated magnetic-field sensors with frequency output , 1997 .

[3]  Lin-Jiunn Tzou,et al.  A low-jitter and low-power phase-locked loop design , 2000, 2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353).

[4]  Igor M. Filanovsky,et al.  Design of a CMOS oscillator with magnetic-field frequency modulation , 1987 .

[5]  Kamran Eshraghian,et al.  Principles of CMOS VLSI Design: A Systems Perspective , 1985 .

[6]  H. Baltes,et al.  Integrated semiconductor magnetic field sensors , 1986, Proceedings of the IEEE.

[7]  Kazusuke Maenaka,et al.  Universal magneto-operational amplifier (MOP) , 1990 .

[8]  Shen-Iuan Liu,et al.  SPICE macro model for MAGFET and its applications , 1999 .

[9]  C. Lyden,et al.  High sensitivity, low power, silicon magnetic field detector , 1994, Proceedings of IEEE Custom Integrated Circuits Conference - CICC '94.

[10]  Pavel Ripka,et al.  Magnetic sensors for industrial and field applications , 1994 .

[11]  Christian Schott,et al.  Modern integrated silicon Hall sensors , 1998 .

[12]  Franco Maloberti,et al.  An integrated microsystem for 3-D magnetic field measurements , 2000, IEEE Trans. Instrum. Meas..