Abstract: In general, according to one embodiment, a semiconductor circuit test method is disclosed. The method can generate a basic format of a test pattern and store the basic format in a test device. The basic format includes at least one parameter and a test program for testing a test target semiconductor circuit. The method can set a predetermined value for the parameter to generate the test pattern including the test program and the parameter set to the predetermined value and supply the test pattern to the test target semiconductor circuit. The method can have store the test program in a first address of a storing module in the test target semiconductor circuit and store the parameter set to the predetermined value in a second address of the storing module. In addition, the method can execute the test program stored in the first address while referring to the parameter stored in the second address.

Abstract: A method and system for correcting timing errors due to thermal changes within a portable computing device are disclosed. The system and method may include calculating an estimate of frequency for a first clock compared to a second clock. The first clock may comprise a crystal oscillator while the second clock comprises a system clock. Next, a sleep state may be calculated for a hardware device, such as radio access technology (“RAT”) module, based on the estimate of frequency for the first clock. An error in the frequency of the first clock that may occur during the sleep state of the hardware device may be calculated. Subsequently, a magnitude of time that corresponds to an actual length of the sleep state relative to the second clock may be calculated so that an internal clock of the hardware devices may be synchronized with the second clock.

Abstract: A test device for a system-on-chip includes a sequential logic circuit and a test circuit. The sequential logic circuit generates a test input signal by converting a serial input signal into a parallel format in response to a serial clock signal and a serial enable signal and generates a serial output signal by converting a test output signal into a serial format in response to the serial clock signal and the serial enable signal. The test circuit includes at least one delay unit that is separated from a logic circuit performing original functions of the system-on-chip, performs a delay test on the at least one delay unit using the test input signal in response to a system clock signal and a test enable signal, and provides the test output signal to the sequential logic circuit, where the test output signal representing a result of the delay test.

Abstract: An example method is provided and includes executing a functional test for an integrated circuit and observing a failure associated with the integrated circuit. The method also includes executing a functional scan mode in order to reproduce the failure associated with the integrated circuit. A functional state of the integrated circuit is locked when the failure occurs, and the functional state is subsequently recovered for a structure test for the integrated circuit. In more particular embodiments, particular states of the functional test are evaluated and compared against other states associated with a model circuit that did not experience any failure in order to identify a latest cycle of the integrated circuit that could trigger the failure and an earliest cycle of the integrated circuit that could observe the failure.

Abstract: Embodiments provide systems, devices, methods, and machine-readable medium for automated debugging of a design under test in a verification environment as part of electronic design automation. Embodiments may automatically identify inputs that are relevant to a bug for a device under test. A failing test run may be taken and rerun several times with small changes in the inputs. If the test is passing, the mutated inputs may be important to reproduce the bug and may be marked as “suspicious”. The result of this process may be a list of suspicious inputs and a shorter and simpler test that still fails. The shorter test may be rerun and fields of the inputs recorded. New tests may be created with mutated fields. Mutated fields that result in passing tests may be considered suspicious fields. Suspicious inputs and fields may be presented to a user as part of an electronic design process.

Abstract: An apparatus and method are provided for detecting an approaching error condition within a data processing apparatus and includes a sequential storage structure arranged to latch an output signal generated by combinatorial circuitry dependent on a second clock signal. The sequential storage structure has a main storage element to latch a value of the output signal for provision to subsequent combinatorial circuitry. The sequential storage structure can be operated in either first or second modes of operation where, in the first mode, the predetermined timing window is ahead of a time at which the main storage element latches said value of the output signal enabling an approaching setup timing error to be detected. In the second mode, the predetermined timing window is after the time at which the main storage element latches said value of the output signal where an approaching hold timing error is detected.

Abstract: Methods and structure for correlating internal operational signals routed via different paths of a test signal selection hierarchy. The structure includes a functional block of circuitry operable to generate internal operational signals and clock signals. The integrated circuit also comprises a test signal selection hierarchy operable to receive the internal operational signals and the clock signals and to selectively route the internal operational signals and the clock signals. Further, structure includes a control unit operable to receive the clock signals from the test signal selection hierarchy, to determine a delay between received clock signals routed via different signaling pathways of the test signal selection hierarchy. The control unit is further operable to program a delay line based upon the delay between the clock signals and based upon internal operational signals correlated with the clock signals.

Abstract: Methods and structure for correlating multiple sets of test output signals in time are provided. The structure includes an integrated circuit comprising a block of circuitry that generates internal operational signals. The circuit also comprises a test multiplexer (MUX) hierarchy that selects subsets of the internal signals and applies the subsets to a testing element. A clock generator generates a clock signal for the selected signals. A test logic timer receives the clock signal and increments a counter value, and applies the counter value to the testing element. An event detector resets the counter value upon detection of an event, such that a first subset of the internal signals acquired from the test MUX hierarchy acquired responsive to detection of a first instance of the event may be correlated in time with a second subset of the internal signals acquired responsive to detection of a second instance of the event.

Abstract: In a radio device such as a receiver or transceiver, a test operation can be performed to determine performance. A received signal can be processed to obtain demodulated samples, which can be provided to a logic to perform a logic operation on the samples to generate a logic output. A storage such as a counter or other mechanism is coupled to the logic to store a count of a number of the logic outputs having an error.

Abstract: Provided is a test apparatus and a test method for substantially synchronizing phases of test signals for each of a plurality of clock domains. The test apparatus tests a device under test including a plurality of clock domains.

Abstract: Circuit for detecting malfunction of a primary clock in SoCs comprises a primary clock circuit having a GRAY code counter for generating a GRAY code sequence based on a number of clock pulses generated Primary clock. A secondary clock circuit is configured to output a secondary clock pulse on each saturation of a secondary clock counter. A clock gated register circuit is clocked by the secondary clock pulse, and is configured to store a plurality of values of the GRAY code sequence, and update the plurality of values of the GRAY code sequence on each saturation of the secondary clock counter. An error detection circuit is configured to output a detection signal for detecting the malfunction of primary clock based on a comparison of the updated plurality of values of the GRAY code sequence with at least one predetermined threshold associated with the malfunction of primary clock.

Abstract: An error controlling system includes a plurality of error generation target circuits, a plurality of pseudo error generating devices each having a pseudo error content holding register that holds directed pseudo error content, each plurality of pseudo error generating device generates a pseudo error corresponding to a pseudo error content held in a respective pseudo error content holding register in at least one of data to be written to one of the plurality of error generation target circuits and data to be read from one of the plurality of error generation target circuits upon being directed to generate the pseudo error, and a pseudo error controlling device that directs the plurality of pseudo error generating devices to generate a pseudo error corresponding to a respective pseudo error content held in each of the pseudo error content holding register provided in each of the plurality of pseudo error generating devices.

Abstract: In described embodiments, a transceiver supports two or more rates using an oversampling clock and data recovery (CDR) circuit sampling high rate data with a predetermined CDR sampling clock. A timing recovery circuit detects and accounts for extra or missing samples when oversampling lower rate data. An edge detector detects each actual data symbol edge and provides for an edge decision offset in a current instant's block of samples. An edge error is generated from the previous instant's actual and calculated edges; and an edge distance between actual edges of the current and previous instants is generated. Filtered edge distance and error are combined to generate a calculated edge position for the data symbol edge for the current instant. The edge decision offset is applied to the current calculated edge position to identify a sample value to generate a decision for the data symbol to detect the current data value.

Abstract: Provided is a test apparatus comprising a synchronization module that operates according to a reference clock and outputs a synchronization signal with a prescribed period, and a test module that operates according to a high-frequency clock with a frequency that is n times a frequency of the reference clock. The test module includes a period emulator that emulates the synchronization signal, a phase shifter that shifts a phase of the high-frequency clock by an amount equal to a result of (i) the product of n and the emulated synchronization phase data by (ii) a period of the reference clock, and a test period generating section that generates a test period pulse signal that transitions at an edge timing of the shifted high-frequency clock and test period phase data indicating a phase difference between the test period signal and an edge timing of the test period pulse signal.

Abstract: A measured device coupled to test equipment providing at least two test factors and receiving a test result is disclosed. The measured device includes a combinatorial logic circuit and a main circuit. The combinatorial logic circuit includes a first storage module and a second storage module. The first storage module stores the test factors according to a first operation clock. The second storage module stores and outputs at least two output factors according to a second operation clock. The frequency of the second operation clock is higher than the frequency of the first operation clock. When the test factors are stored in the first storage module, the test factors stored in the first storage module are served as the output factors and the output factors are output and stored in the second storage module. The main circuit generates the test result according to the output factors output by the second storage module.

Abstract: A packet-based testing capability is provided. The packet-based testing capability is configured to provide a packet-based JTAG (PJTAG) protocol. The PJTAG protocol is an asynchronous protocol configured to support the synchronous JTAG protocol. The PJTAG protocol is configured to convert between JTAG signals and packets configured to transport information of the JTAG signals (e.g., to convert JTAG signals into PJTAG packets at an interface from a JTAG domain to a PJTAG domain and to convert PJTAG packets into JTAG signals at an interface from a PJTAG domain to JTAG domain).

Abstract: A scan clock modifier, a method of providing a variable scan clock, an IC including a scan clock modifier and a library including a cell of a scan clock modifier. In one embodiment, the scan clock modifier includes: (1) logic circuitry configured to provide at least one selected clock signal based on a test scan clock signal and a first clock control signal, both of the test scan clock signal and the first clock control signal received from test equipment and (2) comparison logic configured to provide a scan clock signal based on the at least one selected clock signal and at least one other clock control signal received from the test equipment, wherein the first and the at least one other clock control signals are different clock control signals.

Abstract: A device and a method detect an acceleration of a logic signal expressed by a closeness, beyond a closeness threshold, of at least two variation edges of the logic signal. A first control bit and a second control bit are provided. At each edge of the logic signal, the value of the first control bit is inverted after a first delay and the value of the second control bit is inverted after a second delay. An acceleration is detected when the two control bits have at the same time their respective initial values or their respective inverted initial values. Application is in particular but not exclusively to the detection of error injections in a secured integrated circuit.

Abstract: A system and method is disclosed for managing bookmark buttons on a web browser toolbar. A web browser stores the number of times it is used to navigate to a website. On navigating to a website a predetermined number of times, a bookmark button that links to the website is automatically generated and displayed on the toolbar. The number of bookmark buttons displayed at any one time is limited, and they are arranged by the number of times their associated websites have been viewed. On determining that a new website has been viewed more than a website associated with a currently displayed bookmark button, the currently displayed bookmark button is replaced by a new bookmark button that links to the new website.

Abstract: A delay setting data generator generates delay setting data based on rate data. A variable delay circuit delays the test pattern data by a delay time determined by the delay setting data with reference to a predefined unit amount of delay. First rate data designates the period of the test pattern data with a precision determined by the unit amount of delay. Second rate data designates the period of the test pattern data with a precision higher than that determined by the unit amount of delay. The delay setting data generator outputs a first value and a second value in a time division manner at a ratio determined by the second rate data, the first and second values being determined by the first rate data.

Abstract: A stochastic signal generation circuit includes a signal output circuit and a signal processing circuit connected with the signal output circuit. The signal output circuit includes two matching semiconductor components, wherein the signal output circuit detects a slight mismatch between the two matching semiconductor components, converts the detected slight mismatch into a corresponding electric signal, amplifies the electric signal, and outputs an analog voltage signal. The signal processing circuit converts the analog voltage signal into a stochastic digital signal. Also, a method for generating a stochastic signal is provided. The present invention decreases the cost of the integrated circuit, and better ensures the information security of the electronic products.

Abstract: Disclosed is a system and method for improving the linearity of a clock and data recovery (CDR) circuit. In one embodiment, a data stream is received, and the phase of a clock signal is adjusted using two interpolators. The phase of the output signal of the second interpolator is adjusted simultaneously with, and complementary to, adjusting the phase of the first interpolator. The first interpolator's output signal is injected into a first delay cell in a delay loop having a plurality of delay cells, and the output of the second interpolator is inactivated. When the maximum phase of the first interpolator's output signal is reached, the second interpolator's output signal is injected into another one of the delay cells, and the first interpolator's output signal is inactivated. The data stream is then recovered using the output of the delay loop as a clock signal.

Abstract: The invention disclosed herein provides increased effectiveness of delay and transition fault testing. The method of delay fault testing integrated circuits comprises the steps of creating a plurality of test clock gating groups. The plurality of test clock gating groups comprising elements defining inter-element signal paths within the integrated circuit. Each of the elements of the plurality of test clock gating groups share clock frequency and additional shared characteristics. At least one test signal is commonly and selectively connected through at least one low-speed gate transistor to each of the elements comprising each of the plurality of test clock gating groups based on membership in the test clock gating group. This invention can also be practiced using scan-enable gating groups for the same purposes.

Abstract: Provided is a test apparatus that tests a device under test, having two operational modes which are (i) an edge strobe mode in which the test apparatus judges acceptability of a value of an output signal from the device under test at sequentially designated reference timings, based on expected value information, and (ii) a multi-strobe mode in which the test apparatus judges the acceptability of values of the output signal at a plurality of strobes for each reference timing, based on expected value information, the plurality of strobes being generated based on the reference timing, and comprising a conversion control section that converts an expected value pattern supplied thereto into expected value information to be used in the edge strobe mode or into expected value information to be used in the multi-strobe mode, depending on which of the edge strobe mode and the multi-strobe mode is selected.

Abstract: Systems, controllers, and methods are disclosed, such as an initialization system including a controller configured to receive patterns of read data coupled from a memory device through a plurality of read data lanes. The controller is operable to detect lane-to-lane skew in the patterns of read data. The controller then adjusts the manner in which the read data received through the read data lanes during normal operation are divided into frames. The controller can also couple patterns of command/address bits to the memory device through a plurality of command/address lanes. The memory device can send the received command/address bits back to the controller through the read data lanes. The controller is operable to detect any lane-to-lane skew in the patterns of command/address bits received through the read data lanes to adjust the manner in which the command/address bits coupled through the command/address lanes during normal operation are divided into frames.

Abstract: An information storage medium including two or more recording layers to reproduce or record data by using a same reproducing and/or recording optical system per layer includes error correction code (ECC) blocks recorded onto the two or more recording layers by using two or more data formats used to store user data.

Abstract: A memory controller receives data and phase-providing signals from a memory device. The phase-providing signal is not a clock signal, but is used by the memory controller to phase align a local data-sampling signal with the incoming data. The memory controller samples the data signal with the data-sampling signal. The memory controller can perform maintenance operations to update the phase relationship between the phase-providing and data-sampling signals.

Abstract: Clock signal control circuitry is disclosed along with a method for switching a clock between modes and a computer program product. The clock signal control circuitry is for receiving a clock signal from a clock signal generator and for outputting said clock signal to synchronous circuitry that is to be clocked by said clock signal.

Abstract: A test board includes a plurality of test modules. Each test module stores a first control signal, a data signal, and a second control signal in response to a clock signal, and tests a corresponding device under test (DUT) using the first control signal and the stored data signal in response to the second control signal to generate an error signal indicating whether the DUT is defective. Each test module outputs the first control signal, the data signal, and the second control signal to a test module in a next stage, and each test module of a subsequent stage receives the error signal stored generated by a test module in a previous stage in response to the clock signal.

Abstract: Sequential circuits with error-detection are provided. They may, for example, be used to replace traditional master-slave flip-flops, e.g., in critical path circuits to detect and initiate correction of late transitions at the input of the sequential. In some embodiments, such sequentials may comprise a transition detector with a time borrowing latch.

Abstract: A method of utilizing at least one block of data, wherein the at least one block of data includes a plurality of cells for storing data and at least one error flag bit, the method including: scanning the block of data for errors; determining the error rate of the block of data; and applying an error correction code to data being read from or written to a cell within the at least one block of data, wherein the error correction code is applied based on the error rate, wherein a weak error correction code is applied when the error rate is below an error threshold, and a strong error correction code is applied when the error rate is at or above the error threshold.

Abstract: In operation, a transmitting device selects a synchronization pattern associated with the desired timeslot that is at least mutually exclusive from synchronization patterns associated with other timeslots on the same frequency in the system. Once selected, the transmitting device transmits a burst embedding the synchronization pattern that was selected, where appropriate. If the receiving device detects the synchronization pattern, it immediately synchronizes with the timeslot with confidence that it is synchronizing to the desired timeslot by using sets of synchronization patterns associated with the desired timeslot that are at least mutually exclusive from synchronization patterns associated with the other timeslots on the same frequency.

Abstract: A high-level integrated circuit (“IC”) modeling system (400) includes a first co-simulator (418) modeling a first portion of an IC system and a second co-simulator (419) modeling a second portion of the IC system, each co-simulator operating according to initial simulation operating conditions (426). A co-simulation synchronization interface (424) is configured to automatically change at least one of the initial simulation operating conditions to a triggered operating condition (428) in response to a user-selected triggering signal.

Abstract: An optimized JTAG interface is used to access JTAG Tap Domains within an integrated circuit. The interface requires fewer pins than the conventional JTAG interface and is thus more applicable than conventional JTAG interfaces on an integrated circuit where the availability of pins is limited. The interface may be used for a variety of serial communication operations such as, but not limited to, serial communication related integrated circuit test, emulation, debug, and/or trace operations.

Abstract: The disclosure provides a novel method and apparatus for inputting addresses to devices to select the device TAP for access. Further, the disclosure provides a novel method and apparatus for inputting addresses for selecting device TAPs and for inputting commands for commanding circuitry within the device. The inputting of addresses or the inputting of addresses and commands is initiated by a control bit input on TDI that is recognized during the Run Test/Idle, Pause-DR or Pause-IR TAP states.

Abstract: A method and apparatus are provided for error correction of a communication signal. To allow for retransmission of information in response to error determination with respect to a transmission of the information, the operating sampling rate for a communication channel is increased over its normal sampling rate. At the increased operating rate, retransmissions may be made while at least maintaining the overall data rate of the communication channel with respect to its normal sampling rate. The retransmissions may be conducted using automatic repeat request (ARQ) techniques. In an embodiment, operating at increased sampling rate allows for a decrease in the required signal-to-noise ratio at a given bit error rate for the communication channel.

Abstract: An apparatus that reduces sampling errors for data communicated between devices uses phase information acquired from a timing reference signal such as a strobe signal to align a data-sampling signal for sampling a data signal that was sent along with the timing reference signal. The data-sampling signal may be provided by adjustably delaying a clock signal according to the phase information acquired from the strobe signal. The data-sampling signal may also have an improved waveform compared to the timing reference signal, including a fifty percent duty cycle and sharp transitions. The phase information acquired from the timing reference signal may also be used for other purposes, such as aligning received data with a local clock domain, or transmitting data so that it arrives at a remote device in synchronism with a reference clock signal at the remote device.

Abstract: Embodiments of the invention relate to integrated circuits comprising inputs for receiving an input signal and a plurality of clock signals having a predetermined phase relationship. The integrated circuit may include a plurality of track-and-hold devices and a plurality of slicer devices. Signal outputs of two track-and-hold devices may be coupled to signal inputs of one slicer device, one of the two track-and-hold devices and the slicer device being coupled to a first input configured to receive a first clock signal and the other track-and-hold device being coupled to a second input being configured to receive a second clock signal.

Abstract: Aspects of the invention may be found in a method and system for testing an integrated circuit and may comprise an address selector, data selector and staging register coupled to a signal generator. The address selector may comprise a direct access memory test (DAMT) mode address control input and one or more output address pins coupled to an embedded memory device under test (DUT). The data selector may be coupled to at least one data pin and control pin of the signal generator and may comprise a DAMT mode data control input and at least one data output coupled to embedded memory DUT. A staging register comprising a first output clock rate which is one-quarter (¼) its input clock rate and matches a DUT burst write frequency may be coupled to an input of the data selector. A DAMT mode control may configure the memory DUT for DAMT operation.

Abstract: A multi-channel architecture comprising a central facility that is under clock control of a central facility's clock signal, and a central transfer clock generator adapted for deriving a central transfer clock signal from the central facility's clock signal. The multi-channel architecture further comprises a set of n channels, with n being a natural number, wherein each channel is under clock control of one out of a plurality of clock signals. Each of the channels comprises a channel transfer clock generator adapted for deriving a channel transfer clock signal from a clock signal of the respective channel, wherein the central facility's clock signal and the clock signals of the channels comprise at least two different clock signals. The transfer clock period of the central transfer clock signal is substantially equal to each of the transfer clock periods of the channel transfer clock signals.

Abstract: A system and method for reducing timing errors in automated test equipment (ATE) offering increased data rates for the testing of higher-speed integrated circuits. Embodiments provide an effective mechanism for increasing the data rate of an ATE system by delegating processing tasks to multiple test components, where the resulting data rate of the system may approach the sum of the data rates of the individual components. Each component is able to perform data-dependent timing error correction on data processed by the component, where the timing error may result from data processed by another component in the system. Embodiments enable timing error correction by making the component performing the correction aware of the data (e.g., processed by another component) causing the error. The data may be shared between components using existing timing interfaces, thereby saving the cost associated with the design, verification and manufacturing of new and/or additional hardware.

Abstract: A semiconductor integrated circuit device includes a first clock domain having a plurality of first flip-flops which is configured to operate with a high-speed clock; a second clock domain having a plurality of second flip-flops, composed of a third flip-flop and a plurality of fourth flip-flops, which is configured to operate with a low-speed clock; and a test clock supplying section configured to supply, at a time of delay fault test for the second clock domain, a test clock based on the high-speed clock to the third flip-flop to which data from the first clock domain is input, and not to supply the test clock to the plurality of fourth flip-flops.

Abstract: A mechanism for controlling asynchronous clock domains to perform synchronous operations is provided. With the mechanism, when a synchronous operation is to be performed on a chip, the latches of the functional elements of the chip are controlled by a synchronous clock so that the latches are controlled synchronously even across asynchronous boundaries of the chip. The synchronous operation may then be performed and the chip's functional elements returned to being controlled by a local clock in an asynchronous manner after completion of the synchronous operation. This synchronous operation may be, for example, a power on reset (POR) operation, a manufacturing test sequence, debug operation, or the like.

Abstract: In a test and debug system in which a plurality of selectable modules under test have different operational rates, a selection unit associated with each module is used to control the application of the RCLK signal from the module to the combiner unit, the combiner unit providing a composite RCLK signal. Each selection unit has output signals of RCLK_NE and RCLK_PE signals which are applied to an combiner unit to form the composite RCLK signal. In response to the SELECT signal, the RCLK_NE and RCLK_PE are synchronized with the module RCLK signal. When the SELECT signal is removed, the RCLK_NE and RCLK_PE signals are continuously applied to the combiner unit.

Abstract: A multiport memory is provided with multiple data access paths A, B, each having a respective independent clock signal CLKA, CLKB. During self test operation a duplicate clock enable signal DPCLKTESTEN is used to enable one of these clock signals CLKA, CLKB to be used as a shared clock signal by all data access paths A, B. An external memory adjust signal EMAA. EMAB is used to adjust one of these shared clock signals to form a modified shared clock signal for at least one of the data paths being tested. In this way, worst-case scenarios can be more readily investigated comprising clocks with the same frequency but small differences in phase.

Abstract: An integrated circuit is configured to receive a test clock input and includes circuitry configured to generate test clocks from the test clock input, and test circuitry configured to use the test clocks in a test mode.

Abstract: According to the invention, an IP core is clocked during a debugging operation by switching from the clock used for testing the device under test to a clock oscillator or any other free-running clock source.

Abstract: A system and method for testing a control module includes a microprocessor, where the microprocessor has a programming environment. The programming environment has a test data structure, a configuration data structure, and a monitor data structure each containing data. At least one test data instance is associated with the test data structure and at least one configuration data instance is associated with the configuration data structure. The configuration data instance is a diagnostic test that monitors a parameter of the microprocessor, and the monitor data structure creates the test data instance such that each test data instance corresponds to one of the configuration data instances. The program includes a first control logic for associating the test data structure, the configuration data structure and the monitor data structure as part of a core infrastructure portion of the programming environment, where the core infrastructure portion of the program is static.

Abstract: A method and apparatus for evaluating and optimizing a signaling system is described. A pattern of test information is generated in a transmit circuit of the system and is transmitted to a receive circuit. A similar pattern of information is generated in the receive circuit and used as a reference. The receive circuit compares the patterns. Any differences between the patterns are observable. In one embodiment, a linear feedback shift register (LFSR) is implemented to produce patterns. An embodiment of the present disclosure may be practiced with various types of signaling systems, including those with single-ended signals and those with differential signals. An embodiment of the present disclosure may be applied to systems communicating a single bit of information on a single conductor at a given time and to systems communicating multiple bits of information on a single conductor simultaneously.

Abstract: A multi-strobe circuit that latches a signal to be tested, an evaluation target, at each edge timing of a multi-strobe signal having a plurality of edges. An oscillator oscillates at a predetermined frequency in synchronization with a reference strobe signal. A latch circuit latches the signal to be tested at an edge timing of an output signal of the oscillator. A gate circuit is provided between a clock terminal of the latch circuit and the oscillator, and makes the output signal of the oscillator pass therethrough for a predetermined period. A clock transfer circuit loads the output signal of the latch circuit at an edge timing of the output signal of the oscillator and performs retiming on the output signal of the latch circuit by using a reference clock.