Electrostatic discharge protection for a magnetoresistive sensor

A method for designing a protection circuit for a magneto-resistive (MR) sensor, the method comprising:

• selecting device parameters for a first N-channel field-effect transistor (NFET) and a second NFET within the protection circuit;
• configuring at least one positive-negative (PN) diode within the protection circuit;
• adjusting device parameters for the first NFET, for the second NFET and for the at least one PN diode;
• selecting substrate bias voltages for the first NFET and for the second NFET;
• configuring a forward-biased diode and a reverse-biased diode within the protection circuit;
• and
• adjusting device parameters for the at least one PN diode, the forward-biased diode and the reverse-biased diode.

A magneto-resistive (MR) sensor device comprising:

• an MR sensor having a safe operating voltage range, a normal operating voltage range within the safe operating voltage range, and two terminals coupled to a read channel circuit, including a positive terminal and a negative terminal;
• an MR sensor protection circuit having:
• a positive protection threshold voltage range outside of and above the normal operating voltage range and within the safe operating voltage range;
• a negative protection threshold voltage range outside of and below the normal operating voltage range and within the safe operating voltage range;
• a field-effect transistor (FET) that is coupled to the positive terminal and to the negative terminal, and configured to, in response to a voltage between the two terminals being within the positive protection threshold voltage range, limit the voltage between the terminals by shunting current between the positive terminal and the negative terminal, and;
• a field-effect transistor (FET) that is coupled to the positive terminal and to the negative terminal, and configured to, in response to the voltage between the two terminals being within the negative protection threshold voltage range, limit the voltage between the terminals by shunting current between the positive terminal and the negative terminal.