Semiconductor temperature sensor with high sensitivity

• US 9,464,942 B2
• Filed: 09/23/2013
• Issued: 10/11/2016
• Est. Priority Date: 01/04/2006
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Liu, Bo
• Primary Examiner(s): KAPLAN VERBITSKY, GAIL
• Application Number:
  US14/034,257
• Publication Number:
  US 20140023114A1
• Time in Patent Office: 1,114 Days
• Field of Search: 374/170, 374/178, 374/1, 374/171, 374/172, 374/173
• US Class Current: 1/1
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence
• CPC Class Codes: G05F 3/267 using both bipolar and field-effect technology

Abstract

A temperature sensor circuit is disclosed. In one embodiment, the temperature sensor comprises an input circuit with a current mirror for forcing a current down a reference stage and an output stage. The reference stage and the output stage include P-N junctions (e.g., using bipolar transistors) with differing junction potentials. By tailoring the resistances in the reference and output stages, the input circuit produces two output voltages, one of which varies predictably with temperature, and one which is stable with temperature. The input circuit is preferably used in conjunction with an amplifier stage which preferably receives both the temperature-sensitive and non-temperature sensitive outputs. Through various resistor configurations in the amplifier stage, the output of the temperature sensor can be made to vary at a higher sensitivity than produced by the temperature-sensitive output of the input circuit. Moreover, as a result of the non-temperature-sensitive output, the output of the temperature sensor is additionally and beneficially tailored in its offset voltage in a temperature-independent manner. The result is a flexible circuit that can achieve very high sensitivities and near-ideal performance even at lower power supply voltages.

Claims

1. A temperature sensor, comprising:

an input circuit for producing a first output voltage that varies predictably with temperature at a first temperature sensitivity and a second output voltage that does not vary with temperature; and

an amplifier stage for receiving the first and second output voltages, wherein the amplifier stage produces a temperature sensor output, wherein a first operational amplifier and a second operational amplifier of the amplifier stage, through variable resistor configurations in the amplifier stage, are adapted to enable the temperature sensor output to be offset by an amount that does not vary with temperature, wherein the first output voltage and the second output voltage are separated by a resistor in the input circuit, and wherein the input circuit comprises a current mirror and P-N junctions that differ in their junction potentials, and further comprises adjustable resistors for producing the first and second output voltages.

5. The temperature sensor of claim 1, wherein the input circuit is to be powered by a power supply voltage, wherein the temperature sensor output is approximately the power supply voltage at a first temperature, and wherein the temperature sensor output is approximately ground at a second temperature.

2. A temperature sensor, comprising:

an input circuit for producing a first output voltage that varies predictably with temperature at a first temperature sensitivity and a second output voltage that does not vary with temperature; and

an amplifier stage for receiving the first and second output voltages, wherein the amplifier stage produces a temperature sensor output, wherein the amplifier stage comprises a first operational amplifier for receiving the first output voltage, and a second operational amplifier for receiving the second output voltage, wherein the first operational amplifier and the second operational amplifier of the amplifier stage, through variable resistor configurations in the amplifier stage, enable the temperature sensor output to be offset by an adjustable offset voltage that does not vary with temperature, and wherein the first output voltage and the second output voltage are separated by a resistor in the input circuit.

3. The temperature sensor of claim 2, further comprising a third operational amplifier for generating an intermediate voltage.

4. The temperature sensor of claim 3, further comprising a fourth operational amplifier for receiving the intermediate voltage and producing the temperature sensor output.

6. The temperature sensor of claim 2, wherein outputs from the first and second amplifiers are used to create an intermediate voltage with the adjustable offset voltage;

and a third amplifier for receiving the intermediate voltage and for producing the temperature sensor output.

7. The temperature sensor of claim 6, wherein the input circuit comprises a current mirror and P-N junctions that differ in their junction potentials, and further comprises adjustable resistors for producing the first and second output voltages.

8. The temperature sensor of claim 6, wherein the input circuit is powered by a power supply voltage, wherein the temperature sensor output is approximately the power supply voltage at a first temperature, and wherein the temperature sensor output is approximately ground at a second temperature.

9. A temperature sensor, comprising:

an input circuit for producing a first output voltage that varies predictably with temperature at a first temperature sensitivity and a second output voltage that does not vary with temperature; and

an amplifier stage for receiving the first and second output voltages, wherein the first output voltage and the second output voltage are separated by a resistor in the input circuit,

wherein the input circuit is operable at a power supply voltage; and

wherein the temperature sensor output is approximately the power supply voltage at a first temperature, and wherein the temperature sensor output is approximately ground at a second temperature.

10. The temperature sensor of claim 9, wherein the input circuit comprises a current mirror and P-N junctions that differ in their voltage drops, and further comprises adjustable resistors for producing the first and second output voltages.

11. A temperature sensor, comprising:

an input circuit for producing a first output voltage that varies predictably with temperature at a first temperature sensitivity and a second output voltage that does not vary with temperature;

an first amplifier for receiving the first output voltage and a second amplifier for receiving the second output voltage; and

a third amplifier for receiving an intermediate voltage and for producing a temperature sensor output with a second temperature sensitivity higher than the first temperature sensitivity, wherein the first output voltage and the second output voltage are separated by a resistor in the input circuit.

12. The temperature sensor of claim 11, wherein the input circuit comprises a current mirror and P-N junctions that differ in their junction potentials, and further comprises adjustable resistors for producing the first and second output voltages.

13. The temperature sensor of claim 11, wherein the third amplifier is configured to amplify the first temperature sensitivity to the second temperature sensitivity by a scalar.

14. The temperature sensor of claim 11, wherein the input circuit is to be powered by a power supply voltage, wherein the temperature sensor is designed to operate within a temperature range from a first temperature to a second temperature.

15. The temperature sensor of claim 11, wherein the temperature sensor output is approximately the power supply voltage at the first temperature.

16. The temperature sensor of claim 11, wherein the temperature sensor output is approximately ground at the second temperature.

17. A temperature sensor designed to operate within a temperature range from a first temperature to a second temperature, comprising:

an input circuit operable at a power supply voltage, the input circuit to produce a first output voltage that varies predictably with temperature at a first temperature sensitivity and a second output voltage that does not vary with temperature; and

an amplifier stage for receiving the first and second output voltages, the amplifier stage to produce a temperature sensor output with a second temperature sensitivity higher than the first temperature sensitivity, and wherein the first output voltage and the second output voltage are separated by a resistor in the input circuit.

18. The temperature sensor of claim 17, wherein the input circuit comprises a current mirror and P-N junctions that differ in their voltage drops, and further comprises adjustable resistors to produce the first and second output voltages.