Method and circuit for generating a higher order compensated bandgap voltage

• US 7,091,713 B2
• Filed: 04/30/2004
• Issued: 08/15/2006
• Est. Priority Date: 04/30/2004
• Status: Expired due to Fees

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Integration Associates, Inc. (Silicon Laboratories Incorporated)
• Inventors: Horváth, András Vince, Erdélyi, János
• Primary Examiner(s): Berhane, Adolf
• Application Number:
  US10/836,750
• Publication Number:
  US 20050242799A1
• Time in Patent Office: 837 Days
• Field of Search: 323/312, 323/313, 323/314, 323/315, 323/907, 327/538, 327/539, 327/540
• US Class Current: 323/314
• CPC Class Codes: G05F 3/30 Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities G05F3/26 takes precedence
• CPC Class Codes: Y10S 323/907 Temperature compensation of semiconductor

Abstract

A method and circuit are shown for generating a higher order compensated bandgap voltage is disclosed, in which a first order compensated bandgap voltage and a linearly temperature dependent voltage are generated. Thereafter, a difference between the linearly temperature dependent voltage and the first order compensated bandgap voltage is generated. The resulting difference voltage is squared, and finally the squared voltage is added to the first order compensated bandgap voltage, resulting in a higher order compensated bandgap voltage. There is also disclosed a higher order temperature compensated bandgap circuit.

Claims

1. A method for generating a higher order compensated bandgap voltage, the method comprising:

generating a first order compensated bandgap voltage;

generating a linearly temperature dependent voltage;

generating a difference voltage based on the difference between the linearly temperature dependent voltage and the first order compensated bandgap voltage;

squaring the difference voltage to create a squared voltage; and

adding the squared voltage to the first order compensated bandgap voltage.

2. The method of claim 1, wherein:

the step of generating a first order compensated bandgap voltage further comprises generating a first order compensated bandgap current that is proportional to the first order compensated bandgap voltage;

the step of generating a linearly temperature dependent voltage further comprises generating a linearly temperature dependent current;

the step of generating a difference voltage based on the difference between the linearly temperature dependent voltage and the first order compensated bandgap voltage further comprises generating a difference current based on the difference between the linearly temperature dependent current and the first order compensated bandgap current

the step of squaring the difference voltage to create a squared voltage further comprises squaring the difference current to create a squared current; and

further includes the step of converting the squared current to a voltage.

3. The method of claim 2, wherein the step of generating a linearly temperature dependent current comprises converting the linearly dependent voltage to current.

4. The method of claim 2, wherein the step of generating a linearly temperature dependent voltage further comprises generating a proportional to absolute temperature (PTAT) current using a transistor.

5. The method of claim 4, wherein the step of generating a proportional to absolute temperature (PTAT) current using a transistor further comprises generating a PTAT current using a bipolar transistor.

6. The method of claim 1, further comprising amplifying at least one of the linearly temperature dependent voltage and the first order compensated bandgap voltage so that the linearly temperature dependent voltage and the first order compensated bandgap voltages are substantially equal in a central region of a compensation temperature range.

7. The method of claim 5, wherein the step of generating a first order compensated bandgap voltage further comprises generating the first order compensated bandgap voltage using at least one bipolar transistor.

8. The method of claim 7, wherein the step of generating a PTAT current using a bipolar transistor further comprises generating a PTAT current using a bipolar transistor having the same structure as at least one of the bipolar transistors used to generate the first order compensated bandgap voltage.

9. The method of claim 7, wherein the step of generating a PTAT current using a bipolar transistor further comprises generating a PTAT current using a bipolar transistors used to generate the first order compensated bandgap voltage.

10. The method of claim 5, wherein the step of generating a proportional to absolute temperature (PTAT) current using a transistor further comprises generating a PTAT current using a plurality of bipolar transistors and generating a PTAT voltage by flowing the PTAT current through a resistor.

11. A higher order temperature compensated bandgap circuit comprising

a first order temperature compensated bandgap circuit for generating a first order temperature compensated output voltage;

a current generator circuit for generating a linearly temperature dependent current;

a voltage to current converter circuit for converting to current the first order temperature compensated output voltage and thereby providing a first order temperature compensated bandgap current;

a multiplier circuit for squaring a difference between said first order temperature compensated bandgap current and said linearly temperature dependent current, and for providing a squared current output;

a current to voltage converter circuit for converting to voltage the squared current output of the multiplier circuit for providing a squared voltage output;

an adder circuit for adding the squared voltage output of the current to voltage converter circuit to the first order temperature compensated output voltage of the first order temperature compensated bandgap circuit.

12. The bandgap circuit of claim 11, in which the multiplier circuit comprises a differential voltage input circuit for generating a differential voltage from said linearly temperature dependent current of said current generator and said first order temperature compensated bandgap current of said voltage to current converter circuit.

13. The bandgap circuit of claim 11, in which the linearly temperature dependent current and the first order compensated bandgap current are each fed through the respective resistors of a pair of two substantially equal resistors.

14. The bandgap circuit of claim 11, in which the first order temperature compensated bandgap circuit comprises a first transistor generating a first I_ptat current and a second transistor generating a second I_ptat current.

15. The bandgap circuit of claim 14, in which the first or second transistor comprises a bipolar transistor.

16. The bandgap circuit of claim 11, further comprising means for amplifying at either or both of the first order compensated bandgap current and the linearly temperature dependent current so that the first order compensated bandgap current and the linearly temperature dependent current are substantially equal to the other current in a central region of a compensation temperature range.

17. The bandgap circuit of claim 16, further comprising either a bandgap current setting resistor or a I_ptat current setting resistor, or both.

18. The bandgap circuit of claim 11, in which a linearly temperature dependent voltage is generated with two transistors having different active areas, where two equal I_ptat currents flowing through said two transistors establish different basis-emitter voltages on the two transistors, and a difference between the basis-emitter voltages is transformed across a resistor fed with a linearly temperature dependent current.

19. The bandgap circuit of claim 18, in which the linearly temperature dependent current being fed through said resistor is the I_ptat current flowing through one of said transistors.

20. The bandgap circuit of claim 18, in which the transistor having a larger active area comprises a plurality of separate and parallel connected transistors.

21. The bandgap circuit of claim 11, in which the voltage to current converter circuit for providing a first order temperature compensated bandgap current comprises an op-amp, which establishes a voltage across a resistor, and thereby generates a current through said resistor.

22. The bandgap circuit of claim 11, in which the first order temperature compensated circuit comprises a transistor, which transistor also generates the linearly temperature dependent current.

23. The bandgap circuit of claim 11, in which the multiplier circuit comprises a four quadrant multiplier.

24. A circuit for generating a higher order compensated bandgap voltage, the circuit comprising:

means for generating a first order compensated bandgap voltage;

means for generating a linearly temperature dependent voltage;

means for generating a difference voltage based on the difference between the linearly temperature dependent voltage and the first order compensated bandgap voltage;

means for squaring the difference voltage to create a squared voltage; and

means for adding the squared voltage to the first order compensated bandgap voltage.

25. The circuit of claim 24, wherein:

the means for generating a first order compensated bandgap voltage further comprises means for generating a first order compensated bandgap current that is proportional to the first order compensated bandgap voltage;

the means for generating a linearly temperature dependent voltage further comprises means for generating a linearly temperature dependent current;

the means for generating a difference voltage based on the difference between the linearly temperature dependent voltage and the first order compensated bandgap voltage further comprises means for generating a difference current based on the difference between the linearly temperature dependent current and the first order compensated bandgap current

the means for squaring the difference voltage to create a squared voltage further comprises means for squaring the difference current to create a squared current; and

further includes means for converting the squared current to a voltage.

26. The method of claim 25, wherein the means for generating a linearly temperature dependent current comprises means for converting the linearly dependent voltage to current.

27. The method of claim 25, wherein the means for generating a linearly temperature dependent voltage further comprises means for generating a proportional to absolute temperature (PTAT) current using a transistor.

28. The method of claim 27, wherein the means for generating a proportional to absolute temperature (PTAT) current using a transistor further comprises means for generating a PTAT current using a bipolar transistor.

29. The method of claim 24, further comprising means for amplifying at least one of the linearly temperature dependent voltage and the first order compensated bandgap voltage so that the linearly temperature dependent voltage and the first order compensated bandgap voltages are substantially equal in a central region of a compensation temperature range.

30. The method of claim 28, wherein the means for generating a first order compensated bandgap voltage further comprises means for generating the first order compensated bandgap voltage using at least one bipolar transistor.

31. The method of claim 30, wherein the means for generating a PTAT current using a bipolar transistor further comprises means for generating a PTAT current using a bipolar transistor having the same structure as at least one of the bipolar transistors used to generate the first order compensated bandgap voltage.

32. The method of claim 30, wherein the means for generating a PTAT current using a bipolar transistor further comprises means for generating a PTAT current using a bipolar transistors used to generate the first order compensated bandgap voltage.

33. The method of claim 28, wherein the means for generating a proportional to absolute temperature (PTAT) current using a transistor further comprises means for generating a PTAT current using a plurality of bipolar transistors and generating a PTAT voltage by flowing the PTAT current through a resistor.