# US 9,435,842 B2 · Circuit and method for detection of IC connection failure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,842 B2 - Document ID: US9435842B2 - Status: Granted - Kind: B2 - Application number: 14/472,179 - Filed: 2014-08-28 - Published: 2015-04-23 - Granted: 2016-09-06 - Earliest claimed: 2013-10-22 - Assignees: NXP B.V. - Applicants: NXP B.V. - Inventors: Cicero Silveira Vaucher; Mingda Huang; Antonius de Graauw - Web page: https://patentgrep.com/patent/US9435842B2 ## CPC - G01R 31/2822: {of microwave or radiofrequency circuits (of attenuation, gain, e.g. using network analyzers G01R27/28)} - G01R 31/71: Testing of solder joints - G01S 7/03: Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver - G01S 7/032: {Constructional details for solid-state radar subsystems} - G01S 7/4017: {of HF systems} - G01S 13/931: of land vehicles - G01R 31/006: {on road vehicles, e.g. automobiles or trucks (testing of ignition installations peculiar to internal combustion engines F02P17/00)} - H01Q 1/2283: {mounted in or on the surface of a semiconductor substrate as a chip-type antenna or integrated with other components into an IC package} - H01Q 1/38: formed by a conductive layer on an insulating support {(patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) ## Abstract The invention provides a testing circuit for testing a connection between a chip and external circuitry. A current source is used to inject a DC current towards the connection to be tested from the chip side. On-chip ESD protection is provided giving a path between the connection to be tested and a fixed voltage line. A shunt path is also coupled to the connection to be tested on the external circuitry side. It is determined if the current source current flows through the ESD protection circuit, and this can be used to determine whether or not the connection to be tested presents an open circuit for the DC test current. ## Claims ### Claim 1 A testing circuit for testing an IC connection between an RF chip and external circuitry, the testing circuit comprising: a current source for injecting a DC current towards the connection to be tested; an on-chip ESD protection circuit which provides a path between one side of the connection to be tested and a fixed voltage line; a shunt path coupled to the other side of the connection to be tested; and a testing unit, wherein the testing unit is adapted to determine if the current source current flows through the ESD protection circuit and thereby determine whether the connection to be tested presents a short circuit for DC, wherein the ESD protection circuit is between one side of the connection to be tested and a constant voltage line, and the shunt path is between the other side of the connection to be tested and a second connection, wherein the current source output is coupled to the second connection. ### Claim 2 (depends on 1) A circuit as claimed in claim 1, wherein the ESD protection circuit is between one side of the connection to be tested and a constant voltage line, and an off-chip shunt path is between the other side of the connection to be tested and a constant voltage line. ### Claim 3 (depends on 2) A circuit as claimed in claim 2, wherein the current source output is coupled to the ESD protection circuit. ### Claim 4 (depends on 1) A circuit as claimed in claim 1, wherein the ESD protection circuit comprises an inductor. ### Claim 5 (depends on 1) A circuit as claimed in claim 1, wherein the shunt path comprises an off-chip RF choke. ### Claim 6 (depends on 1) A circuit as claimed in claim 1, comprising an off-chip series path between the connection to be tested and an antenna port for connection to an antenna. ### Claim 7 (depends on 1) A circuit as claimed in claim 1, wherein the testing unit comprises a voltage comparator circuit for providing an output dependent on whether or not the DC current passes through the ESD protection circuit. ### Claim 8 (depends on 1) An RF circuit comprising an RF chip and a PCB to which the RF chip is connected using a ball grid array, the PCB including an antenna, and a testing circuit as claimed in claim 1, for testing the balls which connect to the antenna terminals. ### Claim 9 A method of testing a connection between an RF chip and external circuitry, comprising: injecting a DC current towards the connection to be tested; providing a path between one side of the connection to be tested and a fixed voltage line through an on-chip ESD protection circuit; providing a shunt path coupled to the other side of the connection to be tested; and determining if the current source current flows through the ESD protection circuit and thereby determine whether the connection to be tested presents a short circuit for DC, wherein the ESD protection circuit is between one side of the connection to be tested and a constant voltage line, and the shunt path is between the other side of the connection to be tested and a second connection, wherein the current source output is coupled to the second connection. ### Claim 10 (depends on 9) A method as claimed in claim 9, comprising providing the ESD protection circuit between the connection to be tested and a constant voltage line, and providing the shunt path between the connection to be tested and a constant voltage line. ### Claim 11 (depends on 9) A method as claimed in claim 9, comprising providing the ESD protection circuit between the connection to be tested and a constant voltage line, and providing an off-chip shunt path between the connection to be tested and a second connection, and coupling the current source output to the second connection. ### Claim 12 (depends on 9) A method as claimed in claim 9, comprising providing the shunt path as an off-chip RF choke. ### Claim 13 (depends on 9) A method as claimed in claim 9, wherein the determining comprises performing a voltage comparison to provide an output dependent on whether or not the DC current passes through the ESD protection circuit. ### Claim 14 A testing circuit for testing a plurality of IC connections between an RF chip and external circuitry, the testing circuit comprising: a first connection and a second connection on an RF chip; a current source for injecting a DC current through the second connection and towards the first connection; an on-chip ESD protection circuit which provides a path between one side of the connections and a fixed voltage line; a shunt path coupled to the other side of the connections; and a testing unit, wherein the testing unit is adapted to determine if the current source current flows out of the RF chip through the second connection and returns into the RF chip through the first connection. ### Claim 15 (depends on 14) The testing circuit of claim 14, wherein the current source current is coupled to an RF choke structure on the external circuitry. ### Claim 16 (depends on 14) The testing circuit of claim 14, wherein the current source current returns the fixed voltage via the first connection and the ESD protection circuit.