Commercial power MESFET's with Ti/W/Au gate metallization show a failure mode consisting of a decrease in Zdss and Vp and an increase in Ro. The failure mechanism was investigated by electrical and structural analyses with SEM, microprobe, and Auger spectrometry, and turns out to be a thermally activated Au-GaAs interdiffusion leading to encroachment of the gate metal on the channel. This may be common to all Au-metallized MESFET's and can lead to burn-out of devices.
Integrated current sensing circuits intended for Smart-Power and embedded applications featuring galvanic isolation are implemented. They are based on magnetic detection using the CMOS compatible split-drain transistor (MAGFET) 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 one the current to be sensed flows through an integrated coil placed atop the split-drain transistor and produces a relatively strong magnetic coupling enough to cause a detectable current. The second approach features an array of 126-paralleled split-drain transistors along a metal strip intended to carry higher current levels. Both techniques were realized as integrated current sensors built in 0.35 m CMOS technology. The calculated and measured sensitivities were around 1μA/A and 0.75μA/A for the Coil and Strip approaches respectively. For a typical single split-drain bias current of 50μA, the minimum detectable current within 1Hz are 2.8 A/ Hz and 42 A/ Hz for the Coil and Strip approaches respectively. The Strip can carry currents up to 500mA, whereas the flowing current in the Coil is limited to 20mA. Thus, the choice is based on the resolution and sensing current level of the application.
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 µm CMOS technology. The calculated and measured sensitivities were around 1 and 0.75 µA/A for the coil and strip approaches, respectively. For a typical single splitdrain bias current of 50 µA, the minimum detectable currents within 1 Hz are 2.8 and 42 µA/ √ Hz 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.Index Terms-Current measurement, noise correlation, split drain.
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