US 2009/0257481 A1 · IDENTIFICATION OF BOARD CONNECTIONS FOR DIFFERENTIAL RECEIVERS

Abstract

Embodiments of the invention include testing arrangements for detecting proper DC-coupled board connections on the input legs of a differential receiver. The testing implementation includes a first test receiver AC-coupled to the connection between the first input/output (I/O) pad and the differential receiver positive input and/or a second test receiver coupled to the connection between the second I/O pad and the differential receiver negative input. The test receiver protects the test receiver input from DC voltages applied to the differential receiver via the differential receiver input. Also, the test receiver includes a high-pass filter arrangement that generates data capable of detecting whether the I/O pad connected to the test receiver has a proper DC-coupled connection or an improper connection when presented with a stimulus pulse. The test receiver is less susceptible to noise because than conventional arrangements that use a low-pass RC filter.

Claims14

Dependent claims

A device for testing the connections to a differential receiver, wherein the differential receiver includes a first positive input connected to a first input/output pad, a second negative input connected to a second input/output pad, and an output, comprising:

at least one test receiver coupled to a corresponding one of the first input/output pad and the second input/output pad;
wherein the test receiver is AC-coupled to the input/output pad in a manner that protects the corresponding input of the differential receiver from DC voltages coupled to the differential receiver via the input of the differential receiver, and
wherein the test receiver includes a high-pass filter arrangement that generates data of a first type if the input/output pad coupled to the test receiver has a proper DC-coupled connection and data of a second type if the input/output pad coupled to the test receiver has an improper connection.

A differential input circuit, comprising:

a differential receiver having a first positive input, a second negative input and an output;
a first input/output pad coupled to the first positive input;
a second input/output pad coupled to the second negative input;
a first test receiver AC-coupled between the first input/output pad and the first positive input;
and
a second test receiver AC-coupled between the second input/output pad and the second negative input,
wherein the first test receiver is AC-coupled to the first input/output pad in a manner that protects the first positive input from DC voltages coupled thereto,
wherein the second test receiver is AC-coupled to the second input/output pad in a manner that protects the second negative input from DC voltages coupled thereto, and
wherein each of the first and second test receivers includes a high-pass filter arrangement that generates data of a first type if the input/output pad coupled thereto has a proper DC-coupled connection and data of a second type if the input/output pad coupled thereto has an improper connection.

6 more elements

Dependencies are inferred from the claim text.

Identification of board connections for differential receivers

Life of this patent

Identification of board connections for differential receivers

Life of this patent

Abstract

Claims14