Devices, systems, and methods for generating a reference voltage

• US 7,994,849 B2
• Filed: 03/31/2008
• Issued: 08/09/2011
• Est. Priority Date: 08/04/2005
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Pan, Dong
• Primary Examiner(s): TRA, ANH QUAN
• Application Number:
  US12/059,357
• Publication Number:
  US 20090243709A1
• Time in Patent Office: 1,226 Days
• Field of Search: 327/539, 327512-513, 323/313, 323/315, 323/316
• 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 configured to generate a first divider network voltage;

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

a differential amplifier operably coupled with the first divider network and the second divider network, and configured to generate a second CTAT signal in response to receiving the first divider network voltage and the second divider network voltage as inputs; and

a differential sensing device operably coupled with the bandgap voltage reference circuit, the differential sensing device including the first CTAT signal operably coupled with an inverting input of the differential sensing device, and the second CTAT signal operably coupled with a non-inverting input of the differential sensing device, wherein the differential sensing device is furthered configured to generate a positive reference signal substantially insensitive to temperature variations over an operating temperature range in response to the first CTAT signal and the second CTAT signal, wherein the positive reference signal is relatively closer, during an offset condition of the first divider network voltage and the second divider network voltage, to an ideal output of the positive reference signal than is a voltage difference between the second CTAT signal and the first divider network voltage, the ideal output being the positive reference signal when the first divider network voltage and the second divider network voltage are equal.

2. The voltage reference generator of claim 1, wherein at least one of the first CTAT signal and the second CTAT signal are 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 configured to scale at least one of the first CTAT signal and the second CTAT signal to cause each of the first CTAT signal and the second CTAT signal to exhibit substantially equivalent variations over the operating temperature range, and wherein the positive reference signal is relatively closer, during the offset condition to the ideal output than is a voltage difference between the second CTAT signal and the first divider network voltage when similarly scaled.

4. The voltage reference generator of claim 1, further comprising a unity gain buffer operably coupled between the bandgap voltage reference circuit and the differential sensing device, the unity gain buffer configured to condition at least one of the first CTAT signal and the second CTAT signal for coupling with the differential sensing device.

5. The voltage reference generator of claim 1, wherein at least one of the first CTAT signal and the second 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.

23. The voltage reference generator of claim 1, wherein the offset condition includes the first divider network voltage having a voltage that is greater than the second divider network voltage.

24. The voltage reference generator of claim 1, wherein the offset condition includes the first divider network voltage having a voltage that is less than the second divider network voltage.

7. A voltage reference generator, comprising:

a bandgap voltage reference circuit including;

a first signal generated from a diode array of a first divider network;

a second signal generated from a second divider network; and

a third signal generated from an output of a differential amplifier in response to the first signal and the second signal being input to the differential amplifier; and

a differential sensing device with an inverting input configured to receive the first signal and a non-inverting input configured to receive the third signal, the differential sensing device configured to generate a reference signal from a difference of the third signal and the first signal, the reference signal being substantially insensitive to temperature variations over an operating temperature range, wherein the reference signal is relatively closer to an ideal reference signal than is a difference in the third signal and the second signal when the first signal and the second signal are unequal, the ideal reference signal being a voltage level for the reference signal when the first signal and the second signal are equal.

8. The voltage reference generator of claim 7, further comprising a unity gain buffer operably coupled between the first 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 the diode array, wherein the first signal is a voltage at a node between the first resistive element and the second resistive element.

10. The voltage reference generator of claim 7, wherein the second divider network comprises a third resistive element operably coupled in series with a diode element, wherein the second signal is a voltage at a node between the third resistive element and the diode element.

11. The voltage reference generator of claim 7, wherein the bandgap voltage reference circuit is configured to use the first 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 each of the first signal and the third signal is configured to exhibit a decrease in voltage during an increase in an operating temperature.

14. The voltage reference generator of claim 7, wherein the differential sensing device comprises an inverting amplifier including the inverting input and the non-inverting input.

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

generating a first voltage at a first node operably coupled between a first resistive element and at least one diode;

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

generating a second CTAT signal in response to receiving the first voltage and the second voltage as inputs to a differential amplifier;

inputting the first CTAT signal to an inverting input of a sensing device;

inputting the second CTAT signal to a non-inverting input of the sensing device; and

subtracting the first CTAT signal from the second CTAT signal to generate a positive reference signal substantially insensitive to temperature variations over an operating temperature range, wherein the positive reference signal has a voltage level that, during an offset of the first voltage and the second voltage, is relatively closer to an ideal output than is a difference between the second CTAT signal and the second voltage, the ideal output being the positive reference signal generated when the first voltage and the second voltage are equal.

16. The method of claim 15, wherein generating the first CTAT signal and the second CTAT signal comprises generating at least one signal that is adapted to be sensitive to temperature variations over the operating temperature range.

17. The method of claim 15, further comprising scaling at least one of the first CTAT signal and the second CTAT signal so each of the first CTAT signal and the second CTAT signal exhibit substantially equivalent variations over the operating temperature range, wherein the positive reference signal has a voltage level that, during the offset of the first voltage and the second voltage, is relatively closer to the ideal output than is a difference between the second CTAT signal and the second voltage that are similarly scaled.

18. The method of claim 15, further comprising buffering at least one of the first CTAT signal and the second CTAT signal prior to inputting to the sensing device.

19. The method of claim 15, wherein at least one of the first CTAT signal and the second CTAT signal includes a nonzero temperature coefficient.

25. The method of claim 15, wherein the generating the second CTAT signal and generating the positive reference signal, includes:

increasing voltages of the second CTAT signal and the positive reference signal when the offset includes the first voltage being less than the second voltage; and

decreasing the voltages of the second CTAT signal and the positive reference signal when the offset includes the first voltage being greater than the second voltage.

20. 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 signal generated by a first divider network having a diode array, a second signal generated by a second divider network, and a third signal generated by a differential amplifier responsive to receiving the first signal and the second signal, wherein the first signal and the third signal are complementary-to-absolute temperature (CTAT) signals; and

a differential sensing device configured to generate a reference signal above a ground potential responsive to sensing the first signal and the third signal, wherein the reference signal is substantially insensitive to temperature variations over an operating temperature range, wherein the reference signal has a voltage that is closer to an ideal reference signal relative to a voltage difference between the third signal and the second signal when there exists an offset voltage between the first signal and the second signal, the ideal reference signal being the reference signal that is generated when the first signal and the second signal are equal.

21. The memory device of claim 20, wherein the reference signal is at a voltage level of approximately 750 mV over an operating temperature range of the voltage reference generator.

22. 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, the first signal generated at a node coupled to a diode array and the second signal generated from a differential amplifier configured to receive the first signal and a third signal as inputs, wherein each of the first signal and the second signal is configured to exhibit a decrease in voltage during an increase in operating temperature;

a differential sensing device configured to generate a positive reference signal substantially insensitive to temperature variations over an operating temperature range from sensing the first signal and the second signal, wherein, during an offset between the first signal and the third signal, a difference between a voltage of the positive reference signal and its ideal voltage is relatively smaller than is a difference between voltages of the second signal and the third signal, the ideal voltage of the positive reference signal being generated when the first and third signal have equal voltages; and

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