A circuit couples a test access port (TAP) having a JTAG interface to another port having a serial interface different from the JTAG interface. The circuit includes a forwarding circuit and a timing control circuit. The forward circuit is coupled to couple a test data in (TDI) terminal, a test data out (TDO) terminal, and a test clock (TCK) terminal of the TAP to an input terminal, an output terminal, and a clock terminal of the another port, respectively. The timing control circuit is coupled to drive a select terminal of the another port with a select signal that activates serial data transfer through the serial interface to a device. The timing control circuit delays assertion of the select signal by a configurable time period after assertion of a shift data state of a state machine of the TAP.

The present disclosure describes novel methods and apparatuses for directly accessing JTAG Tap domains that exist in a scan path of many serially connected JTAG Tap domains. Direct scan access to a selected Tap domain by a JTAG controller is achieved using auxiliary digital or analog terminals associated with the Tap domain and connected to the JTAG controller. During direct scan access, the auxiliary digital or analog terminals serve as serial data input and serial data output paths between the selected Tap domain and the JTAG controller.

One example includes a clock receiver system. The system includes a scan clock generator configured to receive a shift clock signal and a high-speed clock signal and to generate a scan clock signal for a transition fault test (TFT) based on the high-speed clock signal. The scan clock generator can provide the scan clock signal as having a pulse sequence comprising at least one preliminary pulse followed by periodic logic state transitions in a capture window during the TFT. The system also includes receiver logic configured to receive the scan clock signal and being programmed to identify each of the at least one preliminary pulse and the periodic logic state transitions in the capture window to pass the TFT.

A scan test device includes a scan flip flop circuit and a clock gating circuit. The scan flip flop circuit is configured to receive a scan input signal according to a scan clock signal, and to output the received scan input signal to be a test signal. The clock gating circuit is configured to selectively mask the scan clock signal according to a predetermined bit of the test signal and a scan enable signal, in order to generate a test scan clock signal for testing at least one core circuit.

Structural testing of a semiconductor integrated circuit (IC), including scanning test patterns or test conditions into internal circuits of the semiconductor IC, for example from a tester device. A timing margin may be measured during the structural test. The margin is measured based on a characteristic of a comparison between a test signal path of the semiconductor IC and a delayed signal path, the delayed signal path being a signal of the test signal path delayed by a variable delay time. An output of the margin measurement sensor may be scanned out, for instance to the tester device.

The present disclosure describes novel methods and apparatuses for directly accessing JTAG Tap domains that exist in a scan path of many serially connected JTAG Tap domains. Direct scan access to a selected Tap domain by a JTAG controller is achieved using auxiliary digital or analog terminals associated with the Tap domain and connected to the JTAG controller. During direct scan access, the auxiliary digital or analog terminals serve as serial data input and serial data output paths between the selected Tap domain and the JTAG controller.

A test control port (TCP) includes a state machine SM, an instruction register IR, data registers DRs, a gating circuit and a TDO MX. The SM inputs TCI signals and outputs control signals to the IR and to the DR. During instruction or data scans, the IR or DRs are enabled to input data from TDI and output data to the TDO MX and the top surface TDO signal. The bottom surface TCI inputs may be coupled to the top surface TCO signals via the gating circuit. The top surface TDI signal may be coupled to the bottom surface TDO signal via TDO MX. This allows concatenating or daisy-chaining the IR and DR of a TCP of a lower die with an IR and DR of a TCP of a die stacked on top of the lower die.

An integrated circuit includes a data propagation path including a flip-flop. The flip-flop includes a first latch and a second latch. The integrated circuit includes a third latch that acts as a dummy latch. The input of the third latch is coupled to the output of the first latch. The integrated circuit includes a fault detector coupled to the output of the flip-flop and the output of the third latch. The third latch includes a signal propagation delay selected so that the third latch will fail to capture data in a given clock cycle before the second latch of the flip-flop fails to capture the data in the given clock cycle. The fault detector that detects when the third latch is failed to capture the data.

An integrated circuit for transition fault testing comprises a synchronizing circuit including a first set of shift registers coupled to receive a scan enable signal and to provide a synchronizing signal based on the scan enable signal; a clock leaker circuit coupled to the synchronizing circuit and including a second set of shift registers coupled to receive a first clock signal based on the synchronizing signal and to provide a second clock signal that includes a set of pulses; and a multiplexer (MUX) that includes a first input coupled to receive a shift clock, a second input coupled to the clock leaker circuit to receive the second clock signal, and an output configured to provide an output clock signal that includes a second set of pulses.

A method of testing an integrated circuit device, that operates at a clock frequency and that has at least one scan chain that includes a plurality of registers separated by combinatorial logic, includes establishing a respective scan chain test pattern for testing the scan chain where the scan chain test pattern includes a respective bit for each register in the plurality of registers of the scan chain, determining in advance a respective timing delay for each pair of adjacent registers in the scan chain, and, within a single clock period of the clock frequency, applying, in parallel, each bit of the respective scan chain pattern to a respective register in the plurality of registers in the scan chain, each bit of the respective scan chain pattern being applied to its respective register at a respective temporal offset, within the single clock period, based on the respective timing delay.