Temperature compensation circuit for a hall effect element

• US 6,104,231 A
• Filed: 07/19/1994
• Issued: 08/15/2000
• Est. Priority Date: 07/19/1994
• Status: Expired due to Fees

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Kirkpatrick, Richard A. II
• Primary Examiner(s): Wells, Kenneth B.
• Application Number:
  US08/277,388
• Time in Patent Office: 2,219 Days
• Field of Search: 327/511, 327/512, 327/513, 324/251, 324/207.2, 323/294, 323/368, 323/907
• US Class Current: 327/513
• CPC Class Codes: G01R 33/07 Hall effect devices

Abstract

A temperature compensation circuit is provided for use in conjunction with a Hall effect element in which the temperature compensating resistors, or epitaxial resistors, are not placed in the signal loop as portions of the feedback loops of amplifiers. The circuit therefore permits a higher degree of linearity and temperature compensation without inducing the problems that are normally caused by varying voltage potentials across the epitaxial resistors. One embodiment of the circuit also provides a means for clamping, or truncating the output voltage of the circuit to a preselected percentage of the supply voltage even though the supply voltage may vary during the operation of the device. The circuit utilizes several external trimmable resistors to perform final adjustment on the circuit in order to permit individual variations from component to component to be compensated.

Claims

1. A Hall effect element circuit, comprising:

a Hall effect element having a first output signal which is representative of a magnetic field imposed on said Hall effect element;

an amplification circuit having an input connected in signal communication with said first output signal, said amplification circuit having a second output signal which is representative of said magnetic field; and

a temperature compensation circuit for compensating said second output signal for changes in temperature, said temperature compensation circuit having at least one temperature sensitive resistor, said temperature compensation circuit being connected to said amplification circuit to receive said second output signal, said temperature sensitive resistor being connected within said Hall effect element circuit in a manner which prevents changes in said first output signal from affecting a voltage potential across said temperature sensitive resistor.

2. The circuit of claim 1, wherein:

said amplification circuit comprises a first amplifier and a second amplifier, said first amplifier having a first transistor connected between its output and its inverting input, said second amplifier having a second transistor connected between its output and its inverting input; and

a resistor connected between the inverting inputs of said first and second amplifiers.

3. The circuit of claim 2, wherein:

said amplification circuit comprises a third amplifier with its noninverting input connected to an output of said first amplifier and its inverting input connected to an output of said second amplifier, said third amplifier having third and fourth output signals whose difference is representative of said magnetic field.

4. The circuit of claim 3, further comprising:

a fourth amplifier having its noninverting input connected to said third output signal and its inverting input connected to said fourth output signal, said fourth amplifier having a temperature sensitive feedback path connected between its output and its inverting input.

5. The circuit of claim 4, further comprising:

a fifth amplifier having a temperature sensitive signal connected to its noninverting input, said fifth amplifier having its output connected to said noninverting input of said fourth amplifier.

6. The circuit of claim 5, further comprising:

means for variably adjusting the output of said fourth amplifier.

7. The circuit of claim 6, further comprising:

means for variably adjusting said signal connected to said noninverting input of said fifth amplifier.

8. The circuit of claim 7, further comprising:

a sixth amplifier having its inverting input connected to said output of said fourth amplifier.

9. The circuit of claim 8, further comprising:

means for variably adjusting said inverting input of said sixth amplifier.

10. A Hall effect element circuit, comprising:

a Hall effect element having a first output signal which is representative of a magnetic field imposed on said Hall effect element;

an amplification circuit having an input connected in signal communication with said first output signal, said amplification circuit having a second output signal which is representative of said magnetic field, said amplification circuit comprising a first amplifier and a second amplifier, said first amplifier having a first transistor connected between its output and its inverting input, said second amplifier having a second transistor connected between its output and its inverting input; and

a temperature compensation circuit for compensating said second output signal for changes in temperature, said temperature compensation circuit having at least one temperature sensitive resistor, said temperature compensation circuit being connected to said amplification circuit to receive said second output signal, said temperature sensitive resistor being connected within said Hall effect element circuit in a manner which prevents changes in said first output signal from affecting a voltage potential across said temperature sensitive resistor.

11. The circuit of claim 10, further comprising:

a resistor connected between the inverting inputs of said first and second amplifiers.

12. The circuit of claim 11, wherein:

said amplification circuit comprises a third amplifier with its noninverting input connected to an output of said first amplifier and its inverting input connected to an output of said second amplifier, said third amplifier having third and fourth output signals whose difference is representative of said magnetic field.

13. The circuit of claim 12, further comprising:

a fourth amplifier having its noninverting input connected to said third output signal and its inverting input connected to said fourth output signal, said fourth amplifier having a temperature sensitive feedback path connected between its output and its inverting input.

14. The circuit of claim 13, further comprising:

a fifth amplifier having a temperature sensitive signal connected to its noninverting input, said fifth amplifier having its output connected to said noninverting input of said fourth amplifier.

15. The circuit of claim 14, further comprising:

means for variably adjusting the output of said fourth amplifier.

16. The circuit of claim 15, further comprising:

means for variably adjusting said signal connected to said noninverting input of said fifth amplifier.

17. The circuit of claim 16, further comprising:

a sixth amplifier having its inverting input connected to said output of said fourth amplifier.

18. The circuit of claim 17, further comprising:

means for variably adjusting said inverting input of said sixth amplifier.

19. A Hall effect element circuit, comprising:

a Hall effect element having a first output signal which is representative of a magnetic field imposed on said Hall effect element;

an amplification circuit having an input connected in signal communication with said first output signal, said amplification circuit having a second output signal which is representative of said magnetic field, said amplification circuit comprising a first amplifier and a second amplifier, said first amplifier having a first transistor connected between its output and its inverting input, said second amplifier having a second transistor connected between its output and its inverting input, said amplification circuit comprising a third amplifier with its noninverting input connected to an output of said first amplifier and its inverting input connected to an output of said second amplifier, said third amplifier having third and fourth output signals whose difference is representative of said magnetic field;

a temperature compensation circuit for compensating said second output signal for changes in temperature, said temperature compensation circuit having at least one temperature sensitive resistor, said temperature compensation circuit being connected to said amplification circuit to receive said second output signal, said temperature sensitive resistor being connected within said Hall effect element circuit in a manner which prevents changes in said first output signal from affecting a voltage potential across said temperature sensitive resistor;

a resistor connected between the inverting inputs of said first and second amplifiers;

a fourth amplifier having its noninverting input connected to said third output signal and its inverting input connected to said fourth output signal, said fourth amplifier having a temperature sensitive feedback path connected between its output and its inverting input;

a fifth amplifier having a temperature sensitive signal connected to its noninverting input, said fifth amplifier having its output connected to said noninverting input of said fourth amplifier; and

means for variably adjusting the output of said fourth amplifier.

20. The circuit of claim 19, further comprising:

means for variably adjusting said signal connected to said noninverting input of said fifth amplifier;

a sixth amplifier having its inverting input connected to said output of said fourth amplifier; and

means for variably adjusting said inverting input of said sixth amplifier.