Semiconductor temperature sensor using bandgap generator circuit
A combined bandgap generator and temperature sensor for an integrated circuit is disclosed. Embodiments of the invention recognize that bandgap generators typically contain at least one temperature-sensitive element for the purpose of cancelling temperature sensitivity out of the reference voltage the bandgap generator produces. Accordingly, this same temperature-sensitive element is used in accordance with the invention as the means for indicating the temperature of the integrated circuit, without the need to fabricate a temperature sensor separate and apart from the bandgap generator. Specifically, in one embodiment, a voltage across a temperature-sensitive junction from a bandgap generator is assessed in a temperature conversion stage portion of the combined bandgap generator and temperature sensor circuit. Assessment of this voltage can be used to produce a voltage- or current-based output indicative of the temperature of the integrated circuit, which output can be binary or analog in nature.
1. An integrated circuit, comprising:
a first generator for producing a temperature-independent reference voltage, wherein the first generator comprises at least one temperature-sensitive element;
a temperature sensor for indicating a temperature to the integrated circuit via an output, wherein the temperature sensor comprises the at least one temperature-sensitive element such that the at least one temperature-sensitive element is common to both the first generator and the temperature sensor; and
a circuit block distinct from the temperature sensor for receiving the temperature-independent reference voltage.
2. The circuit of claim 1 , wherein the first generator comprises a bandgap generator.
3. The circuit of claim 1 , wherein the at least one temperature-sensitive element comprises a P—N junction.
4. The circuit of claim 1 , wherein the temperature sensor assesses a voltage across the at least one temperature-sensitive element to indicate the temperature to the integrated circuit via the output.
5. The circuit of claim 1 , wherein the temperature sensor assesses a temperature-sensitive voltage indicative of the temperature of at least one temperature-sensitive element.
6. The circuit of claim 1 , wherein the output is binary in nature, and wherein the binary output indicates the temperature relative to a set point temperature.
7. The circuit of claim 6 , wherein the set point temperature is trimmable.
8. The circuit of claim 1 , wherein the output is analog.
9. The circuit of claim 1 , wherein the analog output is represented digitally.
10. The circuit of claim 1 , wherein the temperature sensor receives at least a scalar of the temperature-independent reference voltage.
11. The circuit of claim 1 , wherein the temperature sensor comprises a temperature conversion stage.
12. The circuit of claim 10 , wherein the temperature conversion stage receives at least a scalar of the temperature-independent reference voltage.
13. The circuit of claim 1 , wherein the circuit block comprises a second generator.
14. The circuit of claim 12 , wherein second generator produces a second reference voltage used for sensing the logic values stored in an array of memory cells.
15. An integrated circuit, comprising:
a first generator for producing a temperature-independent reference voltage, wherein the first generator comprises at least one temperature-sensitive element;
a temperature sensor for indicating a temperature to the integrated circuit via an output, wherein the temperature sensor receives a temperature-sensitive voltage indicative of the temperature of the at least one temperature-sensitive element; and
a circuit block distinct from the temperature sensor for receiving the temperature-independent reference voltage.
16. The circuit of claim 15 , wherein the temperature sensor comprises a conversion stage for receiving the temperature-sensitive voltage and for converting that voltage to temperature information interpretable by the integrated circuit.
17. The circuit of claim 16 , wherein the conversion stage also receives the temperature-independent reference voltage.
18. The circuit of claim 17 , wherein conversion stage comprises an operational amplifier for producing the output, and wherein the comparator receives as inputs the temperature-sensitive voltage and a scalar of the temperature-independent reference voltage.
19. The circuit of claim 18 , wherein the scalar is less than 1.
20. The circuit of claim 17 , wherein conversion stage comprises an operational amplifier for producing the output, and wherein the comparator receives as inputs a first voltage and a second voltage, wherein the first voltage is produced by a first voltage divider between the temperature-independent reference voltage and ground, and wherein the second voltage is produced by a second voltage divider between the temperature-independent reference voltage and ground, wherein both the first and second voltage dividers receive the temperature-sensitive voltage as an input.
21. The circuit of claim 16 , wherein conversion stage comprises an analog-to-digital converter for converting the temperature-sensitive voltage to the output.
22. The circuit of claim 16 , wherein the conversion stage comprises a transistor for receiving the temperature-sensitive voltage and for producing a current through the transistor, and wherein the current is input to analog-to-digital converter for producing the output.
23. The circuit of claim 16 , wherein the conversion stage converts the temperature-sensitive voltage to a temperature-sensitive current, and wherein the temperature sensitive current is used to form the output.
24. The circuit of claim 15 , wherein the circuit block comprises a second generator for producing a second reference voltage from the temperature-independent reference voltage.
25. The circuit of claim 24 , further comprising an array of memory cells, and wherein the second reference voltage is used in sensing logic values stored in the memory cells.
26. The method of claim 15 , wherein the temperature-independent reference voltage is approximately equal to 1.2 Volts.