Averaged reference with fault monitoring
The subject disclosure describes a structure and method that generates the average of two or more reference quantities (e.g., reference voltage potentials) and monitors the integrity of the voltage reference potentials. The subject technology produces a reference with improved accuracy and more accurate monitoring compared to traditional techniques. For example, the subject technology provides for a fault circuit that includes a monitoring circuit, and an averaging circuit configured to receive a plurality of reference signals and to produce an averaged reference signal based on the received plurality of reference signals. In some examples, the monitoring circuit is configured to receive the averaged reference signal from the averaging circuit, compare the averaged reference signal to each of the plurality of reference signals, and generate a fault signal when the averaged reference signal deviates from at least one of the plurality of reference signals by at least a threshold value.
1. A circuit to monitor a reference signal, the circuit comprising:
an averaging circuit to generate a combined reference signal using two or more reference signals, the combined reference signal comprising a variance that is smaller than a combined variance of the two or more reference signals;
a monitor circuit comprising:
a comparator circuit, coupled to the averaging circuit, to compare the combined reference signal and at least one reference signal of the two or more reference signals, and
a generator circuit to generate, responsive to an indication that a result of the comparison violates a specified criterion, a fault signal;
an error circuit to generate an offset signal; and
a switching circuit, coupled to the averaging circuit and to the at least one reference signal, to selectively adjust, prior to the comparing, the combined reference signal and the at least one reference signal using the offset signal.
2. The circuit of claim 1 , wherein:
in a first configuration of the switching circuit, to selectively adjust the combined reference signal and the at least one reference signal using the offset signal, the switching circuit is to adjust the combined reference signal using the offset signal to generate an adjusted combined reference signal and the comparator circuit is configured to compare the adjusted combined reference signal to the at least one reference signal; and
in a second configuration of the switching circuit, to selectively adjust the combined reference signal and the at least one reference signal using the offset signal, the switching circuit is to adjust the at least one reference signal using the offset signal to generate an adjusted reference signal and the comparator circuit is configured to compare the adjusted reference signal to the combined reference signal.
3. The circuit of claim 1 , further comprising a control circuit to toggle a selection of the at least one reference signal between the first reference signal of the two or more reference signals and a second reference signal of the two or more reference signals.
4. The circuit of claim 1 ; further comprising a resistor network configured to generate the combined reference signal.
5. The circuit of claim 1 , wherein the combined reference signal comprises an average of the two or more reference signals.
6. The circuit of claim 1 , wherein each of the two or more reference signals comprise a voltage reference.
7. The circuit of claim 1 ; wherein the specified criterion comprises a threshold value for a signal difference between the combined reference signal and the at least one reference signal, the threshold value being derived using a ratio of the combined reference signal to the at least one reference signal of the two or more reference signals.
8. A system to detect a fault in a reference signal, the system comprising:
an averaging circuit configured to receive two or more of reference signals and to generate a combined signal using the two or more reference signals; the combined signal having a variance that is smaller than a total variance of the two or more reference signals;
a switch circuit to select a reference signal from the two or more reference signals;
an error check circuit to generate an error check signal; and
a comparator circuit coupled to the switch circuit and the error check circuit to:
compare the combined signal to the selected reference signal using the error check signal; and
generate a fault signal responsive to the combined signal deviating from the selected reference signal by at least a threshold value.
9. The system of claim 8 , wherein the combined signal comprises an average of the two or more reference signals.
10. The system of claim 8 , wherein the error check circuit is to generate the error check signal based on an indicated system tolerance to errors in the two or more reference signals.
11. The system of claim 8 , wherein the averaging circuit comprises a resistor network configured to generate the combined signal.
12. The system of claim 8 , wherein each of the two or more reference signals comprises a voltage reference.
13. The system of claim 8 , wherein the threshold value comprises a fractional value of the combined signal.
14. The system of claim 8 , wherein the threshold value comprises a ratio of the combined reference signal to at least one reference signal of the two or more reference signals.
15. A method of monitoring a reference signal, the method comprising:
receiving two or more reference signals;
generating an averaged reference signal using the two or more reference signals;
selecting a reference signal from the two or more reference signals;
generating a combined signal by adjusting the averaged reference signal or the selected reference signal using an error check signal;
comparing the selected reference signal or the averaged reference signal to the combined signal;
determining, based on the comparison, whether a fault condition exists; and
generating a fault signal when the fault condition exists.
16. The method of claim 15 , wherein determining whether a fault condition exists comprises determining whether the selected reference signal or the averaged reference signal deviates from the combined signal by at least a failure threshold value.
17. The method of claim 15 , wherein adjusting the averaged reference signal or the selected reference signal using the error check signal comprises combining the averaged reference signal or the selected reference signal with the error check signal.
18. The method of claim 15 , further comprising providing the averaged reference signal or the selected reference signal to a load when a fault condition does not exist.
19. The method of claim 15 , wherein generating the averaged reference signal comprises using a resistor network to average the two or more reference signals.
20. The method of claim 15 , further comprising determining the error check signal based on an indicated tolerance to errors in the selected signal.