Magnetically Coupled Current Sensors Using CMOS Split-Drain Transistors

Integrated current-sensing circuits intended for smart-power and embedded applications featuring galvanic isolation are implemented. They are based on magnetic detection using a CMOS-compatible split-drain transistor that provides a very linear output current versus magnetic field. Two approaches ar...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2009-07, Vol.24 (7), p.1733-1736
Main Authors: Castaldo, F.C., Mognon, V.R., dos Reis Filho, C.A.
Format: Article
Language:English
Subjects:
Application specific integrated circuits
Applied sciences
Arrays
CMOS
CMOS technology
Coils
Coils (strip)
Coupling circuits
Current measurement
Design. Technologies. Operation analysis. Testing
Electric currents
Electronics
Exact sciences and technology
Galvanizing
Integrated circuits
Magnetic fields
Magnetic sensors
noise correlation
Semiconductor device measurement
Semiconductor devices
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Semiconductors
Sensors
split drain
Strip
Strips
Transistors
Voltage
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Summary:Integrated current-sensing circuits intended for smart-power and embedded applications featuring galvanic isolation are implemented. They are based on magnetic detection using a CMOS-compatible split-drain transistor that provides a very linear output current versus magnetic field. Two approaches are used to generate the magnetic field: the coil approach and the strip approach. In the first, the current to be sensed flows through an integrated coil placed atop the split-drain transistor and produces a magnetic coupling strong enough to cause a detectable current. The second approach features an array of 126 paralleled split-drain transistors placed along a metal strip intended to carry higher current levels. Both techniques were realized as integrated current sensors built in 0.35 mum CMOS technology. The calculated and measured sensitivities were around 1 and 0.75 muA/A for the coil and strip approaches, respectively. For a typical single split-drain bias current of 50 muA, the minimum detectable currents within 1 Hz are 2.8 and 42 muA/radicHz for the coil and strip approaches, respectively. The strip can carry currents up to 500 mA, whereas the flowing current in the coil is limited to 20 mA. Thus, the choice is based on the resolution and sensing current level of the application.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2009.2014133