Voltage generator with multiple voltage vs. temperature slope domains

1. An electronic circuit, comprising:

a reference voltage generator, comprising:

a first candidate circuit configured to generate a first candidate reference voltage,

a second candidate circuit configured to generate a second candidate reference voltage, and

a selector circuit configured to select one of the first and second candidate reference voltages; and

a third circuit configured to generate a power supply voltage based on the selected candidate reference voltage,

wherein, at temperatures which are greater than a crossover temperature, the first candidate reference voltage is greater than the second candidate reference voltage, wherein, at temperatures which are less than the crossover temperature, the first candidate reference voltage is less than the second candidate reference voltage, and wherein, at the crossover temperature, the first candidate reference voltage is equal to the second candidate reference voltage,

wherein the first candidate circuit is configured to cause the first candidate reference voltage to change by an first amount in response to changing a temperature from a first temperature value to a second temperature value, wherein the second candidate circuit is configured to cause the second candidate reference voltage to change by a second amount in response to changing the temperature from the first temperature value to the second temperature value, and wherein the first amount is greater than the second amount.

2. The electronic circuit of claim 1 , wherein the second amount is substantially zero.

3. The electronic circuit of claim 1 , wherein the selector circuit is configured to select a maximum of the first candidate reference voltage and the second candidate reference voltage.

4. The electronic circuit of claim 1 , wherein the third circuit is configured to receive the selected candidate reference voltage.

5. The electronic circuit of claim 1 , wherein the third circuit is configured to receive a level shifted version of the selected first or second candidate reference voltage.

6. The electronic circuit of claim 1 , wherein the third circuit comprises a voltage regulator, and wherein the voltage regulator is configured to generate the power supply voltage for a digital circuit and an analog circuit.

7. The electronic circuit of claim 6 , wherein the electronic circuit is specified to function at a particular temperature value less than the crossover temperature, wherein the first candidate circuit is configured to generate the first candidate reference voltage with a particular reference voltage value at the particular temperature, wherein the voltage regulator is configured to generate the power supply voltage with a particular power supply voltage value in response to receiving a voltage of the particular reference voltage value, and wherein the analog circuit is configured to not function with the particular power supply voltage value at the particular temperature.

8. A method of operating an electronic circuit, the electronic circuit comprising:

a reference voltage generator, comprising:

first and second candidate circuits, and

a selector circuit; and

a third circuit,

the method comprising:

with the first candidate circuit, generating a first candidate reference voltage;

with the second candidate circuit, generating a second candidate reference voltage;

with the selector circuit, selecting one of the first and second candidate reference voltages;

with the third circuit generating a power supply voltage based on the selected candidate reference voltage,

wherein, at temperatures which are greater than a crossover temperature, the first candidate reference voltage is greater than the second candidate reference voltage, wherein, at temperatures which are less than the crossover temperature, the first candidate reference voltage is less than the second candidate reference voltage, and wherein, at the crossover temperature, the first candidate reference voltage is equal to the second candidate reference voltage;

with the first candidate circuit, causing the first candidate reference voltage to change by an first amount in response to changing a temperature from a first temperature value to a second temperature value; and

with the second candidate circuit causing the second candidate reference voltage to change by an second amount in response to changing the temperature from the first temperature value to the second temperature value,

wherein the first amount is greater than the second amount.

9. The method of claim 8 , further comprising, with the selector circuit selecting a maximum of the first candidate reference voltage and the second candidate reference voltage.

10. The method of claim 8 , further comprising at least one of:

A) with the third circuit, receiving the selected candidate reference voltage; and

B) with the third circuit, receiving a level shifted version of the selected first or second candidate reference voltage.

11. The method of claim 8 , further comprising, with a voltage regulator generating the power supply voltage for a digital circuit and an analog circuit.

12. The method of claim 11 , wherein the electronic circuit is specified to function at a particular temperature value less than the crossover temperature, the method further comprising, with the first candidate circuit is configured to generate the first candidate reference voltage with a particular reference voltage value at the particular temperature, wherein the voltage regulator is configured to generate the power supply voltage with a particular power supply voltage value in response to receiving a voltage of the particular reference voltage value, and wherein the analog circuit is configured to not function with the particular power supply voltage value at the particular temperature.

13. An electronic circuit, comprising:

a reference voltage generator, comprising:

a first candidate circuit configured to generate a first candidate reference voltage,

a second candidate circuit configured to generate a second candidate reference voltage, and

a selector circuit configured to select one of the first and second candidate reference voltages; and

a third circuit configured to generate a power supply voltage based on the selected candidate reference voltage,

wherein, at temperatures which are greater than a crossover temperature, the first candidate reference voltage is greater than the second candidate reference voltage, wherein, at temperatures which are less than the crossover temperature, the first candidate reference voltage is less than the second candidate reference voltage, and wherein, at the crossover temperature, the first candidate reference voltage is equal to the second candidate reference voltage,

wherein the third circuit is configured to receive a level shifted version of the selected first or second candidate reference voltage.

14. The electronic circuit of claim 13 , wherein the third circuit comprises a voltage regulator, and wherein the voltage regulator is configured to generate the power supply voltage for a digital circuit and an analog circuit.

15. An electronic circuit, comprising:

a reference voltage generator, comprising:

a first candidate circuit configured to generate a first candidate reference voltage,

a second candidate circuit configured to generate a second candidate reference voltage, and

a selector circuit configured to select one of the first and second candidate reference voltages; and

a third circuit configured to generate a power supply voltage based on the selected candidate reference voltage,

wherein, at temperatures which are greater than a crossover temperature, the first candidate reference voltage is greater than the second candidate reference voltage, wherein, at temperatures which are less than the crossover temperature, the first candidate reference voltage is less than the second candidate reference voltage, and wherein, at the crossover temperature, the first candidate reference voltage is equal to the second candidate reference voltage,

wherein the third circuit comprises a voltage regulator,

wherein the voltage regulator is configured to generate the power supply voltage for a digital circuit and an analog circuit,

wherein the electronic circuit is specified to function at a particular temperature value less than the crossover temperature, wherein the first candidate circuit is configured to generate the first candidate reference voltage with a particular reference voltage value at the particular temperature, wherein the voltage regulator is configured to generate the power supply voltage with a particular power supply voltage value in response to receiving a voltage of the particular reference voltage value, and wherein the analog circuit is configured to not function with the particular power supply voltage value at the particular temperature.

16. The electronic circuit of claim 15 , wherein the third circuit is configured to receive at least one of the selected candidate reference voltage and a level shifted version of the selected first or second candidate reference voltage.

17. A method of operating an electronic circuit, the electronic circuit comprising:

a reference voltage generator, comprising:

first and second candidate circuits, and

a selector circuit; and

a third circuit,

the method comprising:

with the first candidate circuit, generating a first candidate reference voltage;

with the second candidate circuit, generating a second candidate reference voltage;

with the selector circuit, selecting one of the first and second candidate reference voltages;

with the third circuit generating a power supply voltage based on the selected candidate reference voltage,

wherein, at temperatures which are greater than a crossover temperature, the first candidate reference voltage is greater than the second candidate reference voltage, wherein, at temperatures which are less than the crossover temperature, the first candidate reference voltage is less than the second candidate reference voltage, and wherein, at the crossover temperature, the first candidate reference voltage is equal to the second candidate reference voltage; and

with the third circuit, receiving a level shifted version of the selected first or second candidate reference voltage.

18. The method of claim 17 , further comprising:

with a voltage regulator generating the power supply voltage for a digital circuit and an analog circuit.

19. A method of operating an electronic circuit, the electronic circuit comprising:

a reference voltage generator, comprising:

first and second candidate circuits, and

a selector circuit; and

a third circuit,

the method comprising:

with the first candidate circuit, generating a first candidate reference voltage;

with the second candidate circuit, generating a second candidate reference voltage;

with the selector circuit, selecting one of the first and second candidate reference voltages;

with the third circuit generating a power supply voltage based on the selected candidate reference voltage,

wherein, at temperatures which are greater than a crossover temperature, the first candidate reference voltage is greater than the second candidate reference voltage, wherein, at temperatures which are less than the crossover temperature, the first candidate reference voltage is less than the second candidate reference voltage, and wherein, at the crossover temperature, the first candidate reference voltage is equal to the second candidate reference voltage; and

with a voltage regulator generating the power supply voltage for a digital circuit and an analog circuit,

wherein the electronic circuit is specified to function at a particular temperature value less than the crossover temperature, the method further comprising, with the first candidate circuit is configured to generate the first candidate reference voltage with a particular reference voltage value at the particular temperature, wherein the voltage regulator is configured to generate the power supply voltage with a particular power supply voltage value in response to receiving a voltage of the particular reference voltage value, and wherein the analog circuit is configured to not function with the particular power supply voltage value at the particular temperature.

20. The method of claim 19 , further comprising:

with the third circuit, receiving at least one of the selected candidate reference voltage and a level shifted version of the selected first or second candidate reference voltage.