The X-Hall Sensor: Toward Integrated Broadband Current Sensing

Abstract

This article presents the X-Hall sensor, a viable sensing architecture for implementing a silicon-integrated, broadband, current/magnetic sensor. The X-Hall sensor overcomes the bandwidth limit of the state-of-the-art Hall sensors by replacing the spinning-current technique with dc-biased-based passive offset compensation. In this way, the X-Hall architecture removes the methodological bandwidth limit due to the spinning-current technique and allows for exploiting the Hall probe up to its practical limit, which is set by the parasitic capacitive effects. Moreover, the X-Hall architecture allows pushing the practical bandwidth limit at higher frequencies due to both the removal of the switches inherent in the spinning-current approach and a specially designed analog front end. To this end, a differential-difference current-feedback amplifier (DDCFA) is proposed as an analog front end in the X-Hall sensor. A prototype of the proposed X-Hall architecture is implemented in bipolar-CMOS- DMOS (BCD) 0.16-μm silicon technology to experimentally assess the performance of the X-Hall architecture. The passive offset compensation implemented into the X-Hall architecture is frequency-independent and preserves an adequate offset reduction performance, though less efficient than the spinning-current technique operated at low frequency. Experimental dynamic tests on the prototype identify the presence of an additive parasitic dynamic perturbation due to the package that prevents from fully exploiting the X-Hall prototype up to its designed bandwidth limit. However, the implementation of a postdeemphasis digital filter allows us to mitigate for the dynamic perturbation and experimentally achieve a sensor bandwidth of 4 MHz, which is the broadest bandwidth ever demonstrated by a purely Hall-effect based sensor.