Gated ring oscillator linearization

1. An apparatus comprising:

a time-to-digital converter (TDC) configured to:

receive a signal; and

generate a measurement result indicating a time between start and stop events of the signal; and

a processor coupled to the TDC and configured to:

receive the measurement result;

compare the measurement result to a target value; and

determine a non-linearity model configured to correct a variance of the measurement result from the target value.

2. The apparatus of claim 1 , wherein the TDC is a gated ring oscillator (GRO) based TDC.

3. The apparatus of claim 1 , wherein the non-linearity model is implemented as a look-up table.

4. The apparatus of claim 1 , wherein the non-linearity model is implemented as a polynomial function.

5. The apparatus of claim 1 , further comprising a multiplexer having a first input configured to receive a calibration signal, a second input configured to receive an operating mode signal, and an output coupled to the TDC, the multiplexer configured to:

receive a control signal;

provide the calibration signal as the signal responsive to the control signal having an asserted value; and

provide the operating mode signal as the signal responsive to the control signal having a de-asserted value.

6. The apparatus of claim 1 ,

wherein the TDC is configured to:

receive a second signal; and

generate a second measurement result indicating a time between start and stop events of the second signal; and

wherein the processor is configured to:

receive the second measurement result; and

process the second measurement result according to the non-linearity model to provide a corrected result, wherein the corrected result compensates for non-linearities in the second measurement result.

7. The apparatus of claim 1 , wherein the signal includes multiple pulses having a different duration determined as a multiple of a period of a clock signal.

8. A method, comprising:

receiving, by a gated ring oscillator (GRO) based time-to-digital converter (TDC), a calibration signal;

measuring, by the GRO based TDC, the calibration signal to provide a measurement result, the measurement result including variance from a target value; and

processing the measurement result to determine a non-linearity model, the non-linearity model defining the variance of the measurement result from the target value.

9. The method of claim 8 , wherein the target value is a value indicative of a linear response.

10. The method of claim 8 , wherein the non-linearity model is implemented as a look-up table.

11. The method of claim 8 , wherein the non-linearity model is implemented as a polynomial function.

12. The method of claim 8 , further comprising:

receiving an operating mode signal;

measuring the operating mode signal to provide a second measurement result, the second measurement result including variance from a target value; and

processing the second measurement result according to the non-linearity model to compensate for the variance in the second measurement result from the target value.

13. The method of claim 12 , further comprising a processor determining the non-linearity model and processing the second measurement result according to the non-linearity model.

14. The method of claim 8 , wherein processing the measurement result to determine the non-linearity model comprises comparing the measurement result to the target value to determine the variance of the measurement result from the target value.

15. A method, comprising:

receiving an operating mode signal;

measuring, by a gated ring oscillator (GRO) based time-to-digital converter (TDC), the operating mode signal to provide a measurement result, the measurement result including variance from a target value; and

processing the measurement result according to a non-linearity model defining the variance of the measurement result from the target value to provide a corrected result.

16. The method of claim 15 , wherein the target value is a value indicative of a linear response.

17. The method of claim 15 , wherein the corrected result includes less variance from the target value than does the measurement result.

18. The method of claim 15 , further comprising:

receiving a calibration signal;

measuring the calibration signal to provide a second measurement result, the second measurement result including variance from the target value; and

processing the second measurement result to determine the non-linearity model, the non-linearity model defining the variance of the second measurement result from the target value.

19. The method of claim 18 , wherein the calibration signal is received and measured by a GRO based TDC.

20. The method of claim 18 , wherein processing the measurement result to determine the non-linearity model comprises comparing the measurement result to the target value to determine the variance of the measurement result from the target value.