A multi-die chip module (MCM) comprises a first die containing a first test controller and a second die containing a second test controller coupled to the first die via an interconnect. The first test controller is configured to place the first die in either a shift mode or a capture mode. The second controller is configured to place the second die in either the shift mode or the capture mode. After a scan shift operation, scan cells are initialized to predetermined values. During the capture operation one die remains in the shift mode and the other die enters the capture mode so that as test bits are shifted into registers associated with output pads on the die in the shift mode, the other die is in the capture mode and captures signals on input pads associated with that die, enabling scan based at-speed testing of the interconnect.

A test circuit, provided to a semiconductor device including a plurality of semiconductor chips, includes: a test clock terminal provided to a first chip; a plurality of clock paths disposed between the first chip and a second chip through which the test clock is transmitted from the first chip to the second chip; a test unit provided to the second chip for testing the second chip by using the test clock transmitted to the second chip; a clock detection unit provided to the second chip, and detects the test clock that is received through each of the plurality of clock paths; and a clock path selection unit which is provided to the second chip, selects a first clock path among the plurality of clock paths as a test clock path, and supplies the test clock transmitted through the test clock path to the test unit.

During functional/normal operation of an integrated circuit including multiple independent processing elements, a selected independent processing element is taken offline and the functionality of the selected independent processing element is then tested while the remaining independent processing elements continue functional operation. To minimize voltage drops resulting from current fluctuations produced by the testing of the processing element, clocks used to synchronize operations within each partition of a processing element are staggered. This varies the toggle rate within each partition of the processing element during the testing of the processing core, thereby reducing the resulting voltage drop. This may also improve test quality within an automated test equipment (ATE) environment.

Disclosed herein are exemplary embodiments of a so-called “X-press” test response compactor. Certain embodiments of the disclosed compactor comprise an overdrive section and scan chain selection logic. Certain embodiments of the disclosed technology offer compaction ratios on the order of 1000×. Exemplary embodiments of the disclosed compactor can maintain about the same coverage and about the same diagnostic resolution as that of conventional scan-based test scenarios. Some embodiments of a scan chain selection scheme can significantly reduce or entirely eliminate unknown states occurring in test responses that enter the compactor. Also disclosed herein are embodiments of on-chip comparator circuits and methods for generating control circuitry for masking selection circuits.

Testing of die on wafer is achieved by; (1) providing a tester with the capability of externally communicating JTAG test signals using simultaneously bidirectional transceiver circuitry, (2) providing die on wafer with the capability of externally communicating JTAG test signals using simultaneously bidirectional transceiver circuitry, and (3) providing a connectivity mechanism between the bidirectional transceiver circuitry's of the tester and a selected group or all of the die on wafer for communication of the JTAG signals.

Disclosed is a device for detecting the margin of a circuit operating at an operating speed. The device includes: a signal generating circuit generating an input signal including predetermined data; a first adjustable delay circuit delaying the input signal by a first delay amount and thereby generating a delayed input signal; a circuit under test performing a predetermined operation based on a predetermined operation timing and thereby generating a to-be-tested signal according to the delayed input signal; a second adjustable delay circuit delaying the to-be-tested signal by a second delay amount and thereby generating a delayed to-be-tested signal; a comparison circuit comparing the data included in the delayed to-be-tested signal with the predetermined data based on the predetermined operation timing and thereby generating a comparison result; and a calibration circuit determining whether the circuit under test passes a speed test according to the comparison result.

A chain of flip-flops is tested by passing a reference signal through the chain. The reference signal is generated from a test pattern that is cyclically fed back at the cadence of a clock signal. The reference signal propagates through the chain of flip-flops at the cadence of the clock signal to output a test signal. A comparison is carried out at the cadence of the clock signal of the test signal and the reference signal, where the reference signal is delayed by a delay time taking into account the number of flip-flops in the chain and the length of the test pattern. An output signal is produced, at the cadence of the clock signal, as a result of the comparison.

IEEE 1149.1 Test Access Ports (TAPs) may be utilized at both IC and intellectual property core design levels. TAPs serve as serial communication ports for accessing a variety of embedded circuitry within ICs and cores including; IEEE 1149.1 boundary scan circuitry, built in test circuitry, internal scan circuitry, IEEE 1149.4 mixed signal test circuitry, IEEE P5001 in-circuit emulation circuitry, and IEEE P1532 in-system programming circuitry. Selectable access to TAPs within ICs is desirable since in many instances being able to access only the desired TAP(s) leads to improvements in the way testing, emulation, and programming may be performed within an IC. A TAP linking module is described that allows TAPs embedded within an IC to be selectively accessed using 1149.1 instruction scan operations.

A test mode circuit of a semiconductor device includes a test mode activating signal generation unit suitable for generating a test mode activating signal in response to a test signal; a test clock generation unit suitable for generating a plurality of test clocks in response to the test mode activating signal and a control clock; a test control signal generation unit suitable for generating test control signals based on the plurality of test clocks of a control signal input cycle, wherein the plurality of test clocks have the control signal input cycle and a data input cycle; and an internal control signal generation unit suitable for generating a plurality of control signals to perform a test operation in response to the test control signals and input data.

A processor includes logic to implement a reconfigurable test access port with finite state machine control. A plurality of test access ports may each include a finite state machine for enabling implementation of different test interfaces to the processor, including JTAG IEEE 1149.1, JTAG IEEE 1149.7, and serial wire debug.