DEVICES, SYSTEMS, AND METHODS FOR GENERATING A REFERENCE VOLTAGE

• US 20090243709A1
• Filed: 03/31/2008
• Published: 10/01/2009
• Est. Priority Date: 08/04/2005
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Pan, Dong
• Granted Patent: US 7,994,849 B2
• Time in Patent Office: Days
• US Class Current: 327/539
• 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

Abstract

Methods, devices, and systems are disclosed for a voltage reference generator. A voltage reference generator may comprise a bandgap voltage reference circuit configured to output two complementary-to-absolute-temperature (CTAT) signals. The voltage reference generator may further comprise a differential sensing device configured to sense the two complementary-to-absolute-temperature (CTAT) signals and generate a positive reference signal substantially insensitive to temperature variations over an operating temperature range.

Claims

1. A voltage reference generator, comprising:

a bandgap voltage reference circuit including;

a first divider network including a diode array and configured to generate first complementary-to-absolute-temperature (CTAT) signal; and

a second divider network configured to convey an input to a differential amplifier;

wherein the differential amplifier is configured to output a second complementary-to-absolute-temperature (CTAT) signal; and

a differential sensing device configured to sense the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal and to generate a positive reference signal substantially insensitive to temperature variations over an operating temperature range;

wherein the second complementary-to-absolute-temperature (CTAT) signal is operably coupled to a non-inverting input of the differential sensing device.

2. The voltage reference generator of claim 1, wherein at least one of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal is adapted to be sensitive to temperature variations over the operating temperature range.

3. The voltage reference generator of claim 1, wherein the differential sensing device is further adapted to scale at least one of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal to cause each of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal to exhibit substantially equivalent variations over the operating temperature range.

4. The voltage reference generator of claim 1, further comprising a unity gain buffer adapted to condition at least one of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal for coupling with the differential sensing device.

5. The voltage reference generator of claim 1, wherein at least one of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal comprises a nonzero temperature coefficient.

6. The voltage reference generator of claim 1, wherein the positive reference signal is approximately 750 mV over the operating temperature range.

7. A voltage reference generator, comprising:

a bandgap voltage reference circuit including;

a first output signal operably coupled between a resistive element and a diode array of a first divider network; and

a second output signal operably coupled to an output of a differential amplifier; and

a differential sensing device operably coupled to the first output signal and the second output signal and configured to generate a reference signal substantially insensitive to temperature variations over an operating temperature range;

wherein the second output signal is operably coupled to a non-inverting input of the sensing device.

8. The voltage reference generator of claim 7, further comprising a unity gain buffer operably coupled between the first output signal and the differential sensing device.

9. The voltage reference generator of claim 7, wherein the first divider network comprises a first resistive element operably coupled in series between a second resistive element and a diode array, wherein the first output signal is operably coupled between the first resistive element and the second resistive element.

10. The voltage reference generator of claim 7, further comprising a second divider network comprising a resistive element operably coupled in series with a diode element and configured to convey an input to the differential amplifier.

11. The voltage reference generator of claim 7, wherein the bandgap voltage reference circuit is configured to use the first output signal as an internal voltage level.

12. The voltage reference generator of claim 7, wherein the reference signal comprises a positive reference signal over the operating temperature range.

13. The voltage reference generator of claim 7, wherein the positive reference signal is approximately 750 mV for a supply voltage of approximately 1.0 V.

14. The voltage reference generator of claim 7, wherein each of the first output signal and the second output signal is configured to exhibit a decrease in voltage during an increase in an operating temperature.

15. The voltage reference generator of claim 7, wherein the differential sensing device comprises an inverting amplifier having an inverting input operably coupled to the first output signal.

16. A method for generating a reference signal, comprising:

generating a first voltage at a node operably coupled between a resistive element and a diode array to generate a first complementary-to-absolute-temperature (CTAT) signal;

differentially sensing the first voltage and a generated second voltage to generate a second complementary-to-absolute-temperature (CTAT) signal;

inputting the second complementary-to-absolute-temperature (CTAT) signal to a non-inverting input of a sensing device;

differentially sensing the first complementary-to-absolute-temperature CTAT signal and the second complementary-to-absolute-temperature CTAT signal; and

generating a positive reference signal substantially insensitive to temperature variations over an operating temperature range.

17. The method of claim 16, wherein generating a first complementary-to-absolute-temperature (CTAT) signal and a second complementary-to-absolute-temperature (CTAT) signal comprises generating at least one complementary-to-absolute-temperature (CTAT) signal that is adapted to be sensitive to temperature variations over the operating temperature range.

18. The method of claim 16, further comprising scaling at least one of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal so each of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal exhibit substantially equivalent variations over the operating temperature range.

19. The method of claim 16, further comprising buffering at least one of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal for differentially sensing.

20. The method of claim 16, wherein at least one of the first complementary-to-absolute-temperature (CTAT) signal and the second complementary-to-absolute-temperature (CTAT) signal includes a nonzero temperature coefficient.

21. The method of claim 16, wherein generating the positive reference signal comprises generating the reference signal of approximately 750 mV over the operating temperature range.

22. A memory device, comprising:

a memory array; and

a voltage reference generator operably associated with the memory array, including;

a bandgap voltage reference circuit including a first complementary-to-absolute-temperature (CTAT) signal operably coupled to a first divider network having a diode array and a second complementary-to-absolute-temperature (CTAT) signal operably coupled to an output of a differential amplifier; and

a differential sensing device for generating a reference signal above a ground potential, wherein the reference signal is substantially insensitive to temperature variations over an operating temperature range responsive to sensing the first and second complementary-to-absolute-temperature (CTAT) signals, wherein a non-inverting input of the differential sensing device is operably coupled to the second complementary-to-absolute-temperature (CTAT) signal.

23. The memory device of claim 22, wherein the voltage reference generator is configured to enhance data retention by the memory array.

24. The memory device of claim 23, wherein the reference signal is at a voltage level of approximately 750 mV.

25. An electronic system, comprising:

at least one processor;

at least one memory device; and

at least one voltage reference generator operably associated with the at least one memory device and comprising;

a bandgap voltage reference circuit including a first signal and a second signal, each of the first signal and the second signal configured to exhibit a decrease in voltage during an increase in operating temperature;

a differential sensing device for generating a positive reference signal substantially insensitive to temperature variations over an operating temperature range from sensing the first signal and the second signal; and

a unity gain buffer having a non-inverting input configured to receive the first signal and output a buffered signal to an inverting input of the differential sensing device.