Temperature compensated Hall-effect sensor apparatus

A Hall-effect sensor for producing an electrical signal corresponding to magnetic flux density, comprising:

• a Hall-effect element having bias electrodes for supply of bias voltage to the Hall-effect element and output electrodes at which an output voltage is produced, the output voltage having an offset voltage component and a signal voltage component;
• voltage regulator means having a pair of output terminals connected to the bias electrodes and operative for supplying a regulated voltage to the bias electrodes, the regulated voltage being maintained at a substantially constant value independent of load and ambient temperature variations, thereby producing an offset voltage component that is substantially constant and independent of variations in ambient temperature and a sensitivity ratio between the signal voltage component and the magnetic flux density that is a decreasing function of temperature;
• and
• a differential amplifier including first and second transistors having input electrodes connected to the output electrodes of the Hall-effect element, a third transistor connected in series with the first and second transistors to control the total current through the first and second transistors, and conductance control means for control of the third transistor to obtain an amplifier gain that is substantially independent of changes in ambient temperature;
• wherein the conductance control means includes a resistor that can be adjusted to provide a desired sensitivity ratio between the signal voltage component and the magnetic flux density, a fourth transistor having a base-emitter junction in parallel with the base-emitter junction of the third transistor, a fifth transistor for supplying current to the parallel-connected base-emitter junctions of the third and fourth transistors, a sixth transistor having a base-emitter junction in parallel with the base-emitter junction of the fifth transistor, and a seventh transistor and having a control electrode to which the regulated voltage is applied, each of the first, second, fifth and sixth transistor being of one conductive type and each of the third, fourth and seventh transistors being of a conductive type that is complementary to the one conductive type;
• and wherein the resistor is connected in series with the seventh transistor.

A Hall-effect sensor for producing an electrical signal corresponding to magnetic flux density, comprising:

• a Hall-effect element having bias electrodes for supply of bias voltage to the Hall-effect element and output electrodes at which an output voltage is produced, the output voltage having an offset voltage component and a signal voltage component;
• voltage regulator means having a pair of output terminals connected to the bias electrodes and operative for supplying a regulated voltage to the bias electrodes, the regulated voltage being maintained at a substantially constant value independent of load and ambient temperature variations, thereby producing an offset voltage component that is substantially constant and independent of variations in ambient temperature and a sensitivity ratio between the signal voltage component and the magnetic flux density that is decreasing function of temperature;
• and
• a measuring circuit connected to the output electrodes, the measuring circuit including a comparator having a pair of input terminals, amplifier means for amplifiying signals developed at the output electrodes and applying the amplified signals to the input terminals of the comparator, a resistor connected in series with one of the input terminals of the comparator, shunt transistor means coupled in a shunt relationship with the input terminals of the comparator, the comparator being switched from a first state to a second state at a positive trip level that is a function of the resistance value of the resistor, and control means coupled to the output of the comparator and arranged to control the shunt transistor means to provide hysteresis with the comparator being switched from the second state to the first state at a desired negative trip level.

The Hall-effect sensor for producing an electrical signal corresponding to magnetic flux density, comprising:

• a Hall-effect element having bias electrodes for supply of bias voltage to the Hall-effect element and output electrodes at which an output voltage is produced, the output voltage having an offset voltage component and a signal voltage component;
• voltage regulator means having a pair of output terminals connected to the bias electrodes and operative for supplying a regulated voltage to the bias electrodes, the regulated voltage being maintained at a substantially constant value independent of load and ambient temperature variations, thereby producing an offset voltage component that is substantially constant and independent of variations in ambient temperature and a sensitivity ratio between the signal voltage component and the magnetic flux density that is a decreasing function of temperature;
• and
• amplifier means having offset voltage compensation means for compensating for the offset voltage of the Hall-effect element, the amplifier means including a pair of transistors having input electrodes connected to the output electrodes of the Hall-effect element and a pair of resistors connected in series with the transistors, the resistance values of the resistors being adjustable relative to each other to provide the offset voltage compensation.

A Hall-effect sensor for producing an electrical signal corresponding to magnetic flux density, comprising:

• a Hall-effect element having bias electrodes for supply of bias voltage to the Hall-effect element and output electrodes at which an output voltage is produced, the output voltage having an offset voltage component and a signal voltage component;
• voltage regulator means having a pair of output terminals connected to the bias electrodes and operative for supplying a regulated voltage to the bias electrodes, the regulated voltage being maintained at a substantially constant value independent of load and ambient temperature variations, thereby producing an offset voltage component that is substantially constant and independent of variations in ambient temperature and a sensitivity ratio between the signal voltage component and the magnetic flux density that is a decreasing function of temperature;
• and
• a differential amplifier including first and second transistors having input electrodes connected to the output electrodes of the Hall-effect element, a third transistor connected in series with the first and second transistors to control the total current through the first and second transistors, and conductance control means for control of the third transistor to obtain an amplifier gain that is substantially independent of changes in ambient temperature;
• wherein the conductance control means includes a resistor that can be adjusted to provide a desired sensitivity ratio between the signal voltage component and the magnetic flux density.

The Hall-effect sensor for producing an electrical signal corresponding to magnetic flux density, comprising:

• a Hall-effect element having bias electrodes for supply of bias voltage to the Hall-effect element and output electrodes at which an output voltage is produced, the output voltage having an offset voltage component and a signal voltage component;
• voltage regulator means having a pair of output terminals conencted to the bias electrodes and operative for supplying a regulated voltage to the bias electrodes, the regulated voltage being maintained at a substantially constant value independent of load and ambient temperature variations, thereby producing an offset voltage component that is substantially constant and independent of variations in ambient temperature and a sensitivity ratio between the signal voltage component and the magnetic flux density that is a decreasing function of temperature;
• and
• a measuring circuit connected to the output electrodes, the measuring circuit including a detector circuit that operates at controllable threshold levels, a resistor having a resistance value that is a decreasing function of temperature substantially the same as that of the sensitivity ratio, and means for controlling the threshold levels in accordance with the resistance value of the resistor, thereby adjusting the threshold level in proportion to the sensitivity ratio.