Methods and systems for detecting defects in serial link transceivers
View Patent ↗Methods and systems for detecting defects in serial link transceivers. Defect detection includes detecting open circuits in one or more of the transmission lines, detecting short circuits between one or more of the transmission lines and a power supply, detecting short circuits between the transmission lines, or detecting short circuits across optional AC-couplings in the transmission lines. The detection can include direct or indirect detection of voltage or current.
1. A differential receiver, comprising:
a differential input configured to receive a differential signal having an input common-mode voltage;
a common-mode control circuit configured to generate a correction signal based on the input common mode voltage; and
a monitoring system configured to monitor the correction signal, and determine if the correction signal exceeds a threshold, thereby representing a defect in a differential transmission line coupled to the differential input.
2. The differential receiver of claim 1 , wherein the correction signal is one of an AC correction signal or a DC correction signal.
3. The differential receiver of claim 1 , wherein the monitoring circuit outputs an indication of a defect in the differential transmission line when the correction signal exceeds the threshold.
4. The differential receiver of claim 3 , wherein the indication identifies whether the correction signal is an AC correction signal or a DC correction signal.
5. The differential receiver of claim 3 , wherein the indication identifies when the AC correction signal tracks the changes in the differential signal.
6. The apparatus according to claim 1 , wherein the monitoring circuit is configured to output an indication of a defect when an open circuit exists in the differential transmission line.
7. The differential receiver according to claim 1 , wherein the differential transmission line includes AC-coupled differential transmission lines, and wherein the monitoring system detects short circuits across AC-coupling capacitors in one of the AC-coupled differential transmission lines.
8. The differential receiver according to claim 1 , wherein the monitoring system is configured to output an indication of a defect upon any of the following conditions:
an AC correction signal is detected exceeding a predetermined threshold;
a DC correction signal is sensed exceeding a predetermined threshold; or
no signal is received by the differential receiver and the correction signal is sensed by the monitoring system exceeding a predetermined threshold.
9. The apparatus according to claim 1 , wherein the monitoring system is configured to output an indication of a defect when a short circuit exists between the differential transmission line and a power supply.
10. The apparatus according to claim 1 , wherein the monitoring system is configured to output an indication of a defect when a short circuit exist in the differential transmission line.
11. The apparatus according to claim 1 , wherein the monitoring system is configured to output an indication of a defect when a short circuit exists across an AC coupling in an AC-coupled differential transmission lines.
12. In a differential receiver having a differential input, a method of detecting defects in a differential transmission line coupled to the differential input, comprising the steps of:
receiving a differential signal having an input common-mode voltage at the differential input;
generating a correction signal based on the input common-mode voltage; and
monitoring the correction signal to determine when the correction signal exceeds a threshold, thereby representing a defect in the differential transmission line coupled to the differential input.
13. The method of claim 12 , further comprising the step of outputting an indication of the defect in the transmission line when the correction signal exceeds the threshold.
14. The method of claim 12 , wherein the indication identifies whether the correction signal is an AC correction signal or a DC correction signal.
15. A differential receiver, comprising:
a differential input configured to receive a differential signal having an input common-mode voltage;
a common-mode control circuit configured to generate a correction signal based on the input common mode voltage; and
a monitoring system configured to monitor the correction signal, and determine if the correction signal substantially tracks the differential signal, thereby representing a defect in a differential transmission line coupled to the differential input.
16. The differential receiver of claim 15 , wherein the correction signal is added to a portion of the differential input to adjust the input common mode voltage to a desired common mode voltage.
17. The differential receiver of claim 15 , wherein if the correction signal substantially tracks the differential signal, then the monitoring system is configured to indicate the defect is one of: an open circuit in the differential transmission line connected to the differential input, or a short circuit between the differential transmission line connected to the differential input and a power supply.
18. A differential receiver, comprising:
a differential input configured to receive a differential signal having an input common-mode voltage;
a common-mode control circuit configured to generate a correction signal based on the input common mode voltage; and
a monitoring system configured to monitor the correction signal and determine if the correction signal is an AC correction signal or a DC correction signal, thereby identifying a type of defect in a differential transmission line coupled to the differential input.
19. The differential receiver of claim 18 , wherein the AC correction signal identifies one of the following types of defects: an open circuit in the differential transmission line, or a short between the differential transmission line and a power supply.
20. The differential receiver of claim 18 , wherein the DC correction signal indicates the defect is a short circuit between component transmission lines of the differential transmission line, if substantially no differential signal is detected at the differential input.