Numerical band gap

• US 8,130,025 B2
• Filed: 04/17/2008
• Issued: 03/06/2012
• Est. Priority Date: 04/17/2007
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Kutz, Harold
• Primary Examiner(s): O NEILL, PATRICK
• Application Number:
  US12/104,672
• Publication Number:
  US 20080258804A1
• Time in Patent Office: 1,419 Days
• Field of Search: 327/512, 327/513, 327538-540, 327/542, 374/178
• US Class Current: 327/513
• CPC Class Codes: H03K 19/177 arranged in matrix form

Abstract

A system includes a bandgap temperature sensor to generate multiple base-emitter voltages. The system also include a controller to detect the base-emitter voltages generated by the bandgap temperature sensor and to generate a bandgap reference voltage according to the multiple base-emitter voltage signals, the bandgap reference voltage having a voltage level that remains substantially constant relative to environmental temperature variations.

Claims

1. A device comprising:

a bandgap temperature sensor configured to generate a selected number of base-emitter voltages responsive to receiving a request to generate the selected number of base-emitter voltages; and

a system controller configured to;

select the number of selected base-emitter voltages to be generated responsive to a desired resolution of a bandgap reference voltage,

receive the selected number of base-emitter voltages generated by the bandgap temperature sensor, and

generate the bandgap reference voltage according to the selected number of base-emitter voltages, the bandgap reference voltage remaining substantially constant relative to a temperature associated with the bandgap temperature sensor.

2. The device of claim 1, wherein the system controller is further configured to determine at least one difference in the selected number of base-emitter voltages, and to generate the bandgap reference voltage from the at least one difference in the selected number of base-emitter voltages and at least one of the selected number of base-emitter voltages.

3. The device of claim 2, wherein the system controller is further configured to add the at least one difference in the selected number of base-emitter voltages to one of the selected number of base-emitter voltages to generate the bandgap reference voltage.

4. The device of claim 3, wherein the system controller is further configured to multiply the at least one difference in the base-emitter voltages to a constant value and to add a multiplied difference to one of the selected number of base-emitter voltages to generate the bandgap reference voltage.

5. The device of claim 4, wherein the constant value is based at least in part on a measured characteristic of the bandgap temperature sensor.

6. The device of claim 1 wherein the bandgap temperature sensor includes a variable current source configured to provide a first current to a transistor to generate a first base emitter voltage, and to provide a second current to the transistor to generate a second base-emitter voltage.

7. The device of claim 1, further comprising an analog-to-digital converter configured to convert the selected number of base emitter voltages into digital base-emitter voltage signals, wherein the system controller is configured to generate the bandgap voltage responsive to the digital base-emitter voltage signals.

8. A method comprising:

detecting a selected number of base-emitter voltages generated by a bandgap temperature sensor, the selected number of base-emitter voltages controllable in relation to a desired resolution or granularity of a bandgap reference voltage; and

generating the bandgap reference voltage according to the selected number of base-emitter voltages, the bandgap reference voltage remaining substantially constant relative to environmental temperature variations of the bandgap temperature sensor.

9. The method of claim 8, further comprising:

determining a difference in the selected number of base-emitter voltages; and

generating the bandgap reference voltage from the difference in the selected number of base-emitter voltages and at least one of the selected number of base-emitter voltages.

10. The method of claim 9, wherein the generating the bandgap reference voltage includes adding the difference in the selected number of base-emitter voltages to one of the selected number of base-emitter voltages.

11. The method of claim 10, wherein the generating the bandgap reference voltage includes:

multiplying the difference in the selected number of base-emitter voltages with a constant value; and

adding the multiplied difference to one of the selected number of base emitter voltages.

12. The method of claim 11, wherein the constant value is based at least in part on a measured characteristic of the bandgap temperature sensor.

13. The method of claim 8, further comprising:

generating a first base-emitter voltage responsive to a first current being provided to a transistor;

generating a second base-emitter voltage responsive to a second current being provided to the transistor;

determining a difference between the first base-emitter voltage and the second base-emitter voltage; and

generating the bandgap reference voltage based, at least in part, on the determined difference between the first base-emitter voltage and the second base-emitter voltage.

14. A system comprising:

a memory configured to store computer-executable instructions; and

a microprocessor configured to execute the computer-executable instructions stored in the memory, the computer-executable instructions when executed by the microprocessor, cause the microprocessor to;

receive a selected number of base-emitter voltages generated by a bandgap temperature sensor, the selected number of base-emitter voltages controllable in relation to a desired resolution of a bandgap reference voltage; and

generate the bandgap reference voltage responsive to the selected number of base-emitter voltages, the bandgap reference voltage remaining substantially constant relative to environmental temperature variations of the bandgap temperature sensor.

15. The system of claim 14, wherein the microprocessor is operable to determine a difference in the selected number of base-emitter voltages, and generate the bandgap reference voltage from the difference in the selected number of base-emitter voltages and at least one of the selected number of base-emitter voltages.

16. The system of claim 15 wherein the base-emitter voltages decrease as the environmental temperature increases, and the difference increases as the environment temperature increases.

17. The system of claim 15, wherein the microprocessor is operable to add the difference in the selected number of base-emitter voltages to one of the selected number of base-emitter voltages to generate the bandgap reference voltage.

18. The system of claim 17, wherein the microprocessor is operable to multiply the difference in the selected number of base-emitter voltages to a constant, and add the multiplied difference in the selected number of base-emitter voltages to one of the selected number of base-emitter voltages to generate the bandgap reference voltage.

19. The system of claim 18, wherein the constant is determined based at least in part on a measured characteristic of the bandgap temperature sensor.

20. The system of claim 14, further comprising:

a bandgap temperature sensor configured to generate a first base-emitter voltage when a first current is provided to a transistor and to generate a second base-emitter voltage when a second current is provided to the transistor; and

wherein the microprocessor is caused to determine a difference between the first base-emitter voltage and the second base-emitter voltage, and generate the bandgap reference voltage using the determined difference between the first base-emitter voltage and the second base-emitter voltage.