Variable rate analog-to-digital converter
View Patent ↗An analog-to-digital converter can use a variable sampling rate. By using a variable sampling rate analog-to-digital converter and an anti-aliasing filter lower sampling rates, and accordingly, generally lower power consumption may be achieved. For example, a lower sampling rate can be used when it is determined that no undesirable signals are present and a higher sampling period can be used when an undesirable signal is present. Determining the presence of an undesired signal can be based on signal-to-noise ratio, over-sampling, bit error rate, using a detector, etc. An undesirable signal can be any signal that is close in frequency to a signal of interest or a signal farther away in frequency that has a relatively high amplitude. Sampling rate can be varied in a binary fashion, stepwise, continuously, etc.
1. An electronic device comprising:
an analog-to-digital converter configured to have an adjustable sampling rate; and
a rate adjustment module coupled to the analog-to-digital converter and configured to control the adjustable sampling rate of the analog-to-digital converter by:
monitoring a communication environment and setting the sampling rate so as to eliminate aliasing from an undesired signal in an adjacent communication channel.
2. The device of claim 1 , wherein the condition of the environment is determined by monitoring a signal quality metric.
3. The device of claim 1 , wherein the condition of the environment is determined by over-sampling for a short period of time to determine if an undesirable signal is present.
4. The device of claim 1 , further comprising an RF detector coupled to the adjustment module and configured to monitor the environment.
5. The device of claim 1 , wherein the condition of the environment is determined by monitoring a bit error rate.
6. The device of claim 1 , wherein the sampling rate of the analog-to-digital converter is increased based on locating an undesirable signal close in frequency to a signal of interest.
7. The device of claim 1 , wherein the sampling rate of the analog-to-digital converter is increased based on locating an undesirable signal with a high amplitude relative to a signal of interest.
8. The device of claim 1 , wherein the sampling rate of the analog-to-digital converter is decreased based on locating an undesirable signal distant in frequency to a signal of interest.
9. The device of claim 1 , wherein the sampling rate of the analog-to-digital converter is decreased based on locating an undesirable signal with a low amplitude relative to a signal of interest.
10. The device of claim 1 , wherein the sampling rate of the analog-to-digital converter is decreased based on the absence of an undesirable signal.
11. The device of claim 1 , wherein the sampling rate of the analog-to-digital converter is decreased based on the high quality of a signal of interest.
12. The device of claim 1 , further comprising an anti-aliasing filter coupled to an analog input to the analog-to-digital converter.
13. The device of claim 12 , wherein the analog anti-aliasing filter comprises a passive filter.
14. The device of claim 12 , wherein the analog anti-aliasing filter comprises an RC filter.
15. The device of claim 12 , wherein the analog anti-aliasing filter comprises an active filter.
16. The device of claim 1 , further comprising a digital filter coupled to a digital output of the analog-to-digital converter and configured to digitally filter the output of the analog-to-digital converter.
17. The device of claim 1 , wherein the sampling rate is greater than or equal to two times the highest frequency component of a desired signal.
18. A method of controlling an adjustable sampling rate of an analog-to-digital converter comprising the steps of:
monitoring a communication environment;
determining if an undesired signal is present in a frequency range of interest and
when the undesired signal is detected, setting the sampling rate of the analog-to-digital converter to eliminate aliasing from an undesired signal in the adjacent communication channel.
19. The method of claim 18 , wherein the condition of the environment is determined by monitoring a signal quality metric.
20. The method of claim 18 , wherein the condition of the environment is determined by over-sampling for a short period of time to determine if an undesirable signal is present.
21. The method of claim 18 , further comprising using an RF detector to monitor the environment.
22. The method of claim 18 , wherein the condition of the environment is determined by monitoring a bit error rate.
23. The method of claim 18 , further comprising increasing the sampling rate of an analog-to-digital converter based on locating an undesirable signal close in frequency to a signal of interest.
24. The method of claim 18 , further comprising increasing the sampling rate of an analog-to-digital converter based on locating an undesirable signal with a high amplitude relative to a signal of interest.
25. The method of claim 18 , further comprising increasing the sampling rate of the analog-to-digital converter based on locating an undesirable signal distant in frequency to a signal of interest.
26. The method of claim 18 , wherein the sampling rate of the analog-to-digital converter is decreased based on locating an undesirable signal with a low amplitude relative to a signal of interest.
27. The method of claim 18 , wherein the sampling rate of the analog-to-digital converter is decreased based on the absence of an undesirable signal.
28. The method of claim 18 , wherein the sampling rate of the analog-to-digital converter is decreased based on the high quality of a signal of interest.
29. The method of claim 18 , further comprising filtering an analog input to the analog-to-digital converter.
30. The method of claim 18 , further comprising digitally filtering a digital output of the analog-to-digital converter.
31. The method of claim 18 , further comprising using a sampling rate that is greater than or equal to two times the highest frequency component of a desired signal.