# US 2019/0170823 A1 · Test apparatus and test method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170823 A1 - Document ID: US20190170823A1 - Status: Published application - Kind: A1 - Application number: 16/146,701 - Filed: 2018-09-28 - Published: 2019-06-06 - Earliest claimed: 2017-12-06 - Assignees: Advantest Corporation - Applicants: Advantest Corporation - Inventors: NAGATANI KENICHI - Web page: https://patentgrep.com/patent/US20190170823A1 ## CPC - G01R 31/31725: {Timing aspects, e.g. clock distribution, skew, propagation delay (for tester hardware G01R31/31937)} - G01R 31/31703: {Comparison aspects, e.g. signature analysis, comparators (concerning scan tests G01R31/318566; concerning testers G01R31/3193)} - G01R 31/31709: {Jitter measurements; Jitter generators (measuring jitter, noise figure or signal-to-noise ratio per se G01R29/26; analysis of tester signals G01R31/31901)} - G01R 31/3177: Testing of logic operation, e.g. by logic analysers - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A time measurement unit measures the time interval between edges to be monitored in a signal under test DUT_Output including serial data output from a device under test (DUT) 400. A comparison judgment unit calculates the number of bits of the serial data included between the edges to be monitored, based on the time interval thus measured. Furthermore, the comparison judgment unit compares the number of bits thus calculated with an expected value thereof. ## Claims ### Claim 1 A test apparatus comprising: a time measurement unit operable to measure a time interval between edges monitored in a signal under test including serial data output from a device under test; and a comparison judgment unit operable to calculate a number of bits included between the edges monitored, based on the measured time interval, and to compare the number of bits with an expected value to generate a comparison result. ### Claim 2 (depends on 1) The test apparatus according to claim 1, wherein the time measurement unit is operable to generate a time stamp T[i] for each edge monitored, and wherein the comparison judgment unit is operable to round off a quotient obtained by dividing an edge interval represented by ΔTi=T[i+1]−T[i] by an ideal unit interval to generate a calculation result, and to employ the calculation result as the number of bits of the serial data output. ### Claim 3 (depends on 2) The test apparatus according to claim 2, wherein the time measurement unit comprises: a data decimation unit operable to extract an edge of the signal under test for each N edges, wherein N represents a first integer; and a time stamper operable to assign the time stamp to the edge extracted by the data decimation unit. ### Claim 4 (depends on 3) The test apparatus according to claim 3, wherein the data decimation unit comprises a polarity selector operable to select at least one from a positive edge or a negative edge from the signal under test. ### Claim 5 (depends on 3) The test apparatus according to claim 3, wherein the data decimation unit comprises: a pre-scaler operable to extract an edge for each K edges, wherein K represents a second integer; and an inter-discarder arranged on a downstream stage from the pre-scaler, and operable to extract an edge for each L edges, wherein L represents a third integer. ### Claim 6 (depends on 1) The test apparatus according to claim 1, wherein the comparison judgment unit is mounted in a DSP (Digital Signal Processor). ### Claim 7 A test method for a signal under test including serial data output from a device under test, the test method comprising: measuring a time interval between edges monitored in the signal under test; calculating a number of bits of the serial data output included between the edges monitored, based on the time interval that is measured; and comparing the number of bits that is calculated with an expected value to generate a comparison result. ### Claim 8 (depends on 7) The test method according to claim 7, wherein an edge monitored is extracted for each N edges, and wherein the test method is executed with an i-th edge, an (i+N)-th edge, (i+2×N)-th edge, . . . , as the edge monitored, while incrementing i from 1 to N. ### Claim 9 (depends on 7) The test method according to claim 7, wherein an edge monitored is extracted for each N edges, wherein N is an odd number, and wherein the test method is executed with predetermined edge numbers while repeatedly inputting the signal under test comprising an even number of edges for each pattern period. ### Claim 10 (depends on 1) The test apparatus according to claim 1, wherein the comparison judgment unit is operable to generate a pass/fail signal that corresponds to the comparison result. ### Claim 11 (depends on 10) The test apparatus according to claim 10, wherein a value of the pass/fail signal indicates a pass if the comparison result is a match. ### Claim 12 (depends on 10) The test apparatus according to claim 10, wherein a value of the pass/fail signal indicates a fail if the comparison result is not a match. ### Claim 13 (depends on 7) The test method according to claim 7, further comprising: generating a pass/fail signal that corresponds to the comparison result. ### Claim 14 (depends on 13) The test method according to claim 13, wherein a value of the pass/fail signal indicates a pass if the comparison result is a match. ### Claim 15 (depends on 13) The test method according to claim 13, wherein a value of the pass/fail signal indicates a fail if the comparison result is not a match. ### Claim 16 A test apparatus comprising: a jitter remover operable to remove jitter from a serial data sequence by rounding a calculated number of bits between edges monitored of the serial data sequence to generate a rounded result and by comparing the rounded result with an expected value to generate a comparison result. ### Claim 17 (depends on 16) The test apparatus according to claim 16, wherein the jitter remover comprises: a time measurement unit operable to measure a time interval between the edges monitored; and a comparison judgment unit operable to generate the rounded result based on the time interval and to generate the comparison result. ### Claim 18 (depends on 17) The test apparatus according to claim 17, wherein the time measurement unit is operable to generate a time stamp for each edge monitored. ### Claim 19 (depends on 18) The test apparatus according to claim 18, wherein the time measurement unit comprises: a data decimation unit operable to extract an edge of the serial data sequence for each N edges, wherein N represents a first integer; and a time stamper operable to assign the time stamp to the edge extracted by the data decimation unit. ### Claim 20 (depends on 19) The test apparatus according to claim 19, wherein the data decimation unit comprises a polarity selector operable to select at least one from a positive edge or a negative edge from the serial data sequence.