Noise correlation in dual-collector magnetotransistors

Experimental results of low frequency (1/f) noise in magnetic-field-sensitive dual-collector bipolar transistors are presented that show a strong positive correlation between the noise voltages (converted from corresponding fluctuations in the currents) of the collectors. Hence, operating the magnetotransistor in a differential mode yields very favorable signal-to-noise ratios, even for low magnetic sensitivity. Calculations performed for a magnetotransistor with a sensitivity of only 0.06/T yields a field resolution of 25 nT/√Hz at 1 kHz, in contrast to 14 μT/√Hz in single-ended operation