# US 9,753,087 B2 · Method for testing a multi-chip system or a single chip and system thereof

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- Number: US 9,753,087 B2
- Document ID: US9753087B2
- Status: Granted
- Kind: B2
- Application number: 14/384,172
- Filed: 2012-05-10
- Published: 2015-02-19
- Granted: 2017-09-05
- Earliest claimed: 2012-05-10
- Assignees: Telefonaktiebolaget LM Ericsson (publ)
- Applicants: Gan Wen
- Inventors: Gan Wen
- Web page: https://patentgrep.com/patent/US9753087B2

## CPC

- G01R 31/319: Tester hardware, i.e. output processing circuits
- G01R 31/2851: {Testing of integrated circuits [IC] (G01R31/317 takes precedence; testing individual devices G01R31/26; testing printed circuits G01R31/2801)}
- G01R 31/31723: {Hardware for routing the test signal within the device under test to the circuits to be tested, e.g. multiplexer for multiple core testing, accessing internal nodes (routing the test signal to or from the device under test G01R31/31926)}
- G01R 31/318513: {Test of Multi-Chip-Moduls}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A method for testing a multi-chip system with multiple ports includes determining a test path formed by connecting the multiple ports. The test path is determined in such a way that the internal logic circuit of each chip in the multi-chip system is bypassed. The method further includes injecting a test traffic to the test path, and receiving the test traffic from the test path.

## Claims

### Claim 1

A method for testing a multi-chip system including multiple ports, the method comprising:
determining a test path formed by connecting the multiple ports;
injecting, by a test traffic generator, a test traffic to the test path;
receiving, by the test traffic generator, the test traffic from the test path; wherein:
the test path is determined in such a way that an internal logic circuit of each chip in the multi-chip system is bypassed;
the multiple ports are classified as an external port or an internal port; and
the test path is determined as follows:
for an external port in the multi-chip system, when the external port is a port through which the test traffic is injected to the multi-chip system, it is set as a normal mode, otherwise it is set as a near end loopback mode;
for an internal port at a chip of the multi-chip system, when the internal port is an internal port through which the test traffic is first transmitted to the chip, the internal port is set as the normal mode;
for an internal port at a first chip via which the first chip is connected to a second chip in the multi-chip system:
when the first chip experiences the test traffic earlier than the second chip, the internal port is set as the normal mode, and
when the first chip experiences the test traffic later than the second chip and the internal port is not the internal port through which the test traffic is first transmitted to the first chip, the internal port is set as a bypass mode.

### Claim 2

A method for testing a multi-chip system including multiple ports, the method comprising:
determining a test path formed by connecting the multiple ports;
injecting, by a test traffic generator, a test traffic to the test path;
receiving, by the test traffic generator, the test traffic from the test path;
wherein:
the test path is determined in such a way that an internal logic circuit of each chip in the multi-chip system is bypassed;
the multiple ports are classified as an external port or an internal port; and
the test path is determined as follows:
the external port is set as a normal mode;
for an internal port at a chip of the multi-chip system, when the internal port is an internal port through which the test traffic is first transmitted to the chip, the internal port is set as the normal mode;
for an internal port at a first chip via which the first chip is connected to a second chip in the multi-chip system:
when the first chip experiences the test traffic earlier than the second chip, the internal port is set as the normal mode, and
when the first chip experiences the test traffic later than the second chip and the internal port is not the internal port through which the test traffic is first transmitted to the first chip, the internal port is set as a bypass mode.

### Claim 3

A multi-chip system comprising:
a plurality of integrated circuit chips and a plurality of ports, each port of the plurality of ports operable to transmit or receive a signal;
at least two chips of the plurality of integrated circuit chips comprising:
at least two ports of the plurality of ports;
at least one internal logic circuit; and
a test chain, wherein each of the at least two ports are electrically connected to the test chain;
at least one chip of the plurality of integrated circuit chips comprising logic operable to determine a test path formed by connecting the multiple ports to the test chain so that the internal logic circuit of each of the at least two chips is bypassed;
at least one port of the plurality of ports operable to receive test traffic from a test traffic generator and inject the test traffic to the test path;
at least one port of the plurality of ports operable to receive test traffic from the test path;
wherein:
each port of the plurality of ports is classified as an external port or an internal port; and
the logic of the at least one chip determines the test path as follows:
for an external port in the multi-chip system, when the external port is a port through which the test traffic is injected to the multi-chip system, it is set as a normal mode, otherwise it is set as a near end loopback mode;
for an internal port at a chip of the multi-chip system, when the internal port is an internal port through which the test traffic is first transmitted to the chip, the internal port is set as the normal mode;
for an internal port at a first chip via which the first chip is connected to a second chip in the multi-chip system:
when the first chip experiences the test traffic earlier than the second chip, the internal port is set as the normal mode, and
when the first chip experiences the test traffic later than the second chip and the internal port is not the internal port through which the test traffic is first transmitted to the first chip, the internal port is set as a bypass mode.

### Claim 4

A multi-chip system comprising:
a plurality of integrated circuit chips and a plurality of ports, each port of the plurality of ports operable to transmit or receive a signal;
at least two chips of the plurality of integrated circuit chips comprising:
at least two ports of the plurality of ports;
at least one internal logic circuit; and
a test chain, wherein each of the at least two ports are electrically connected to the test chain;
at least one chip of the plurality of integrated circuit chips comprising logic operable to determine a test path formed by connecting the multiple ports to the test chain so that the internal logic circuit of each of the at least two chips is bypassed;
at least one port of the plurality of ports operable to receive test traffic from a test traffic generator and inject the test traffic to the test path;
at least one port of the plurality of ports operable to receive test traffic from the test path;
wherein:
each port of the plurality of ports is classified as an external port or an internal port; and
the logic of the at least one chip determines the test path as follows:
the external port is set as a normal mode;
for an internal port at a chip of the multi-chip system, when the internal port is an internal port through which the test traffic is first transmitted to the chip, the internal port is set as the normal mode;
for an internal port at a first chip via which the first chip is connected to a second chip in the multi-chip system:
when the first chip experiences the test traffic earlier than the second chip, the internal port is set as the normal mode, and
when the first chip experiences the test traffic later than the second chip and the internal port is not the internal port through which the test traffic is first transmitted to the first chip, the internal port is set as a bypass mode.