Tunable diode protection for GMR and TMR sensors

Abstract

TMR and GMR sensors used today are highly susceptible to ESD damage with failure voltages as low as 0.5 V. Diode protection using a single diode connected in parallel with the sensor does not work for many advanced MR sensors due to the fact that the voltage at which diodes begin conducting significant current exceeds the damage voltage of many advanced MR sensors. This is due to limitations of the band gaps of the diode materials (Si and Ge) and the resistance of the diodes while conducting. Here we report several novel diode protection circuits which enable protecting the most sensitive devices while tuning the circuits to the electrical characteristics of the particular sensor being used.