Patent ID: 11971463
Assignee: ALLEGRO MICROSYSTEMS, LLC
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. MTJ sensing circuit for measuring an external magnetic field and comprising a plurality of MTJ sensor elements connected in a bridge configuration, the MTJ sensing circuit having an input for inputting a bias voltage and generating an output voltage proportional to the external magnetic field multiplied by the bias voltage and a gain sensitivity of the MTJ sensing circuit, wherein the gain sensitivity and the output voltage vary with temperature;
the MTJ sensing circuit further comprising a temperature compensation circuit configured to provide a modulated bias voltage that varies as a function of temperature over a temperature range, such that the output voltage is substantially constant as a function of temperature;
wherein the temperature compensation circuit is configured for generating a plurality of reference voltages, each reference voltage corresponding to a temperature subrange of the temperature range;
wherein the temperature compensation circuit further comprises a plurality of subrange resistors configured to generate a temperature dependent voltage for each subrange resistor, when a temperature dependent proportional-to-absolute-temperature (PTAT) current is forced in the plurality of subrange resistors;
the temperature compensation circuit further comprises a plurality of comparators configured to compare temperature dependent voltages to a plurality of fixed voltage references, each comparator generating a hysteresis comparator output;
the temperature compensation circuit further comprises an array-based memory cell having a plurality of registers, each register representing a bias voltage corresponding to one of the temperature subranges, the array-based memory cell being configured to select one of the register depending on the hysteresis comparator output.