INTEGRATED SILICON MAGNETOTRANSISTORS - HIGH-SENSITIVITY OR HIGH-RESOLUTION

Noise measurements performed for various magnetotransistor (MT) structures show that MTs with a high current gain, βF ≫1 (and conversely very low magnetic sensitivities, ΔIc/(ICB) < 0.1/T) exhibit the unique feature of a strong positive correlation in the collector noise voltages. Consequently, very large signal-to-noise ratios are obtained, resulting in high resolution over large bandwidths (Bmin < 20μT over 100 kHz), at low device operating current, IC < 1 mA. On the other hand, MTs with extremely large sensitivity, ΔIC/ (ICB) > 10/T (βF ≪ 1) and nominally operating at large device currents (Itotal ∼ 8 - 10 mA), lose this unique correlation property, resulting in large output noise and a field resolution that could be inferior in comparison. Pertinent examples are provided that illustrate these findings. © 1990.