High temperature position sensors based on monolithic GaAs Hall IC

A x-plast package procedure for cheap line assembly of high temperature position sensors based on a monolithic GaAs Hall IC was developed. The three stage IC contains a Hall device with constant current source, a dual gate MESFET differential amplifier, and a source follower. The differential amplifier delivers a low frequency gain of 100 to 150, a sensitivity of the Hall IC of 180 V/T with supply voltage of 8 to 15 V and works up to 180 C. The DIOM technique meets the relialility requirement of the sensor and the gain and uniformity demands of the GaAs differential amplifier. The planar technique includes localized ion implantation and self aligned gate definition.