Dynamic, digitally controlled, temperature compensated voltage reference
View Patent ↗A voltage reference is dynamically and digitally controlled by a digital function. The digital function may be implemented as a digital calculation or look up table. Inputs to the function include a modifiable trim value stored in a trim register, and a substrate temperature value. The preset value of the trim register is a trim preset value generated by cutting fuses and/or leaving fuses uncut. The cutting may be performed using laser trimming-devices. The output of the digital function is a corrected reference trim value that controls the gain of a voltage reference amplifier whose input is a band gap based voltage reference, and whose output is a derived voltage reference. The substrate temperature value is provided by a monolithic temperature monitor whose sensor may be on the same die as the derived voltage reference. The derived voltage reference provides a stable reference voltage that is dynamically and digitally controllable, to a host system that requires a voltage reference.
1. A method for digitally controlling a voltage reference, the method comprising:
obtaining an original voltage reference;
generating a trim preset value by performing an initial trimming of the original voltage reference;
generating an intermediate trim value based on the preset trim value;
generating a corrected reference trim value, based on the intermediate trim value and a substrate temperature value; and
setting a gain for a voltage reference amplifier, based on the corrected reference trim value;
wherein said generating the corrected reference trim value is a digitally implemented function;
wherein an input of the voltage reference amplifier is the original voltage reference; and
wherein an output of the voltage reference amplifier is a derived voltage reference.
2. The method of claim 1 further comprising deriving the original voltage reference from a band gap reference.
3. The method of claim 1 , wherein said performing the initial trimming of the original voltage reference comprises one of:
cutting one or more of a plurality of fuses; and
cutting none of the plurality of fuses.
4. The method of claim 3 , wherein said cutting of one or more of the plurality of fuses is accomplished with the use of a laser trimming-device.
5. The method of claim 3 further comprising the plurality of fuses controlling a preset value of a storage element.
6. The method of claim 5 , wherein the storage element is a register.
7. The method of claim 5 , wherein the storage element is a non-volatile memory.
8. The method of claim 5 , wherein the preset value of the storage element is set to the trim preset value.
9. The method of claim 5 further comprising the storage element being read from and written to by one or more of:
a host system; and
a tester.
10. The method of claim 5 further comprising:
storing the intermediate trim value in the storage element; and
providing the intermediate trim value as an output of the storage element.
11. The method of claim 1 , wherein said generating the trim preset value is performed to a default temperature value.
12. The method of claim 1 , wherein said generating the intermediate trim value is performed to an operating temperature range.
13. The method of claim 1 further comprising:
a monolithic temperature-monitor measuring the substrate temperature value; and
the monolithic temperature-monitor providing the substrate temperature value as an input to the digital function.
14. The method of claim 13 , wherein a sensor of the monolithic temperature-monitor is on the same die as the derived voltage reference.
15. A digitally adjusted voltage reference system, the system comprising:
an original voltage reference;
a storage element;
a digital function block; and
a voltage reference amplifier;
wherein the storage element is operable to store an intermediate trim value;
wherein the digital function block is operable to receive the intermediate trim value;
wherein an input of the voltage reference amplifier is the original voltage reference;
wherein the digital function block generates one or more control signals to control a gain of the voltage reference amplifier; and
wherein an output of the voltage reference amplifier is a derived voltage reference.
16. The system of claim 15 , wherein the original voltage reference is derived from a band gap reference.
17. The system of claim 15 further comprising a plurality of fuses;
wherein each fuse of the plurality of fuses is coupled to a respective preset and/or reset input of the storage element;
wherein a trim preset value is generated by performing one of:
cutting one or more of the plurality of fuses; and
cutting none of the plurality of fuses; and
wherein the storage element is operable to receive the trim preset value as an initial value.
18. The system of claim 17 , wherein said cutting one or more of the plurality of fuses is accomplished with the use of a laser trimming-device.
19. The system of claim 15 further comprising a monolithic temperature-monitor;
wherein the monolithic temperature-monitor is operable to measure the substrate temperature value; and
wherein the monolithic temperature-monitor is operable to provide the substrate temperature value as an input to the digital function block.
20. The system of claim 19 , wherein a sensor of the monolithic temperature-monitor is on the same die as the derived voltage reference.
21. The system of claim 15 , wherein the storage element is operable to be read from and written to by one or more of:
a host system; and
a tester.
22. The system of claim 15 , wherein the digital function block comprises one or more algorithms implemented in hardware.
23. The system of claim 15 , wherein the digital function block obtains its output values from one or more lookup tables.
24. The system of claim 15 , wherein the digital function block is user programmable.
25. The system of claim 15 , wherein the storage element comprises one or more D flip-flops.
26. The system of claim 15 , wherein the storage element comprises non-volatile memory.