US-12625173-B2 - Methods and apparatus for in-situ measurement of mutual inductance between embedded interconnects

US12625173B2US 12625173 B2US12625173 B2US 12625173B2US-12625173-B2

Abstract

A system and method for measuring mutual inductance between adjacent first communication transmission line and second communication transmission line is disclosed. The system includes a mutual inductance measurement circuit that includes a coupling generator which biases the first communication transmission line with a current ramp signal; a sample and hold circuit which captures an induced voltage on the second communication transmission line using a switched capacitor storage element; a switched capacitor integrator configured to integrate the induced voltage onto an output voltage node; and a comparator configured to switch states once the switched capacitor integration has surpassed a reference trippoint.

Inventors

Aaron James Bluestone
Erik Stephen DANIEL
Khashayar PIROUZMAND

Assignees

THE BOEING COMPANY

Dates

Publication Date: 20260512
Application Date: 20231031

Claims (20)

1 . A system for measuring mutual inductance between an adjacent first communication transmission line and second communication transmission line, the system comprising: a mutual inductance measurement circuit comprising: a coupling generator which biases the first communication transmission line with a current ramp signal; a sample and hold circuit which captures an induced voltage on the second communication transmission line using a switched capacitor storage element; a switched capacitor integrator configured to integrate the induced voltage onto an output voltage node; and a comparator configured to switch states once the switched capacitor integration has surpassed a reference trippoint.
2 . The system of claim 1 , wherein the coupling generator uses a DC current source and a capacitor to generate a linear voltage ramp and an op-amp feedback circuit which performs voltage-to-current conversion to generate the current ramp signal.
3 . The system of claim 1 , wherein the current ramp signal on the first communication transmission line induces the induced voltage on the second communication transmission line.
4 . The system of claim 1 , wherein the first communication transmission line is an aggressor line.
5 . The system of claim 1 , wherein the second communication transmission line is a victim line.
6 . The system of claim 1 , wherein the first communication transmission line and the second communication transmission line are high-speed analog communications channels.
7 . The system of claim 1 , wherein the first communication transmission line and the second communication transmission line are digital communications channels.
8 . The system of claim 7 , wherein the digital communications channels comprise application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs).
9 . The system of claim 1 , further comprising a processor configured to receive an output from the comparator and determine a magnitude of mutual inductance.
10 . The system of claim 1 , wherein the voltage comparator is a dynamic, clocked voltage comparator.
11 . A method to determine a mutual inductance between a first communication transmission line and a second communication transmission line, the method comprising: providing a periodic coupling current ramp signal to a first communication transmission line that induces a voltage on a nearby second communication transmission line, wherein the voltage is sampled and held on a capacitor; integrating the voltage onto a feedback capacitor of a switched capacitor integrator when the charge is positive due to a positive change in voltage of the periodic coupling ramp signal on the first communication transmission line; integrating the voltage until the voltage crosses a known threshold as measured on a comparator; and counting a number of cycles required to cross the known threshold to infer a mutual inductance between the first communication transmission line and the second communication transmission line.
12 . The method of claim 11 , wherein prior to the providing the periodic coupling ramp signal, the method comprises resetting the switched capacitor integrator by closing and reopening a switch in parallel with the switched capacitive integrator.
13 . The method of claim 11 , wherein the first communication transmission line is an aggressor line.
14 . The method of claim 11 , wherein the second communication transmission line is a victim line.
15 . The method of claim 11 , wherein the first communication transmission line and the second communication transmission line are high-speed analog communications channels.
16 . The method of claim 11 , wherein the first communication transmission line and the second communication transmission line are digital communications channels.
17 . The method of claim 16 , wherein the digital communications channels comprise application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs).
18 . The method of claim 11 , further comprising receiving, at a processor, an output from the comparator circuit and determining a capacitive-based coupling.
19 . A method to determine a mutual inductance between a first communication line and a second communication line, the method comprising: providing a periodic coupling current ramp signal to a first communication transmission line that induces a voltage on a nearby second communication transmission line, wherein the voltage is sampled and held on a first capacitive storage element; providing a periodic current pulse signal to the first communication transmission line that capacitively couples a charge onto the nearby second communication transmission line, wherein a non-ideality of the charge that is capacitively coupled is sampled and held on a second capacitive storage element; removing the charge that is capacitively coupled from a measurement through a differential switched capacitor integrator; integrating the voltage onto a feedback capacitor of the differential switched capacitor integrator when the charge is positive due to a positive change in voltage of the periodic coupling ramp signal on the first communication transmission line; integrating the voltage until the voltage crosses a known threshold as measured on a comparator; and counting a number of cycles required to cross the known threshold to infer a mutual inductance between the first communication transmission line and the second communication transmission line.
20 . The method of claim 19 , wherein prior to the providing the periodic coupling ramp signal, the method comprises resetting the differential switched capacitor integrator by closing and reopening a switch in parallel with the differential switched capacitor integrator.

Description

FIELD This application is directed to methods and apparatus for in-situ measurement of mutual inductance between embedded interconnects. BACKGROUND Mutual coupling/cross talk measurements are usually done with expensive test equipment that requires disconnecting signal wires from a system transmitter and receiver and connecting them to test equipment instead, and then reconnecting them back into the system. This approach tends to have many disadvantages including being both inefficient and time consuming. While several architectures exist for in-situ measurement of coupling capacitance (e.g. charge based capacitance measurement), we believe the following is first of its kind for discerning mutual inductance between coupled nodes/wires/interconnect in embedded environments. SUMMARY According to examples of the present disclosure, a system for measuring mutual inductance between adjacent first communication transmission line and second communication transmission line is disclosed. The system comprises a mutual inductance measurement circuit comprising: a coupling generator (208) which biases the first communication transmission line (306) with a current ramp signal (500); a sample and hold circuit (212) which captures an induced voltage on the second communication transmission line (308) using a switched capacitor storage element; a switched capacitor integrator configured to integrate the induced voltage onto an output voltage node; and a comparator (214) configured to switch states once the switched capacitor integration has surpassed a reference trippoint. The system can include one or more of the following features. The system can further comprise a coupling generator which utilizes a DC current source and a capacitor to generate a linear voltage ramp and an op-amp feedback circuit which performs voltage-to-current conversion to generate the current ramp signal. The current ramp signal on the first communication transmission line induces a voltage on the second communication transmission line. The first communication transmission line is an aggressor line. The second communication transmission line is a victim line. The first communication transmission line and the second communication transmission line are high-speed analog communications channels. The first communication transmission line and the second communication transmission line are digital communications channels. The digital communications channels comprise application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). The system comprises a processor configured to receive an output from the voltage comparator and determine the magnitude of mutual inductance. The voltage comparator is a dynamic, clocked voltage comparator. According to examples of the present disclosure, a method to determine a mutual inductance between a first communication transmission line and a second communication transmission line is disclosed. The method comprises providing a periodic coupling current ramp signal to a first communication transmission line that induces a voltage on a nearby second communication transmission line, wherein the voltage is sampled and held on a capacitor; integrating the voltage onto a feedback capacitor of a switched capacitor integrator when the charge is positive due to a positive change in voltage of the periodic coupling ramp signal on the first communication transmission line; integrating the voltage until it crosses a known threshold as measured on a comparator; and counting a number of cycles required to cross the known threshold to infer a mutual inductance between the first communication transmission line and the second communication transmission line. The method can include one or more the following features. Prior to the providing the periodic coupling ramp signal, the method comprises resetting the switched capacitor integrator by closing and reopening a switch in parallel with the switched capacitive integrator. The first communication transmission line is an aggressor line. The second communication transmission line is a victim line. The first communication transmission line and the second communication transmission line are high-speed analog communications channels. The first communication transmission line and the second communication transmission line are digital communications channels. The digital communications channels comprise application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). The method further comprising receiving, at a processor, an output from the voltage comparator circuit and determining a capacitive-based coupling. According to examples of the present disclosure, a method to determine a mutual inductance between a first communication transmission line and a second communication transmission line is disclosed. The method comprising: providing a periodic coupling current ramp signal to a first communication transmission line that induces a voltage