A circuit comprises a plurality of clock control devices. Each of the clock control devices is configured to generate a scan test clock signal for a particular clock domain in the circuit and comprises circuitry configured to select clock pulses of a fast clock signal as scan capture clock pulses for the particular clock domain based on a particular clock pulse of a slow clock signal and a scan enable signal. The order and spacing between the groups of the scan capture clock pulses for different clock domains correspond to the order and spacing of the clock pulses of the slow clock signal.

A combinational circuit block has input pins configured to receive input digital signals and output pins configured to provide output digital signals as a function of the input digital signals received. A test input pin receives a test input signal. A test output pin provides a test output signal as a function of the test input signal received. A set of scan registers are selectively coupled to either the combinational circuit block or to one another so as to form a scan chain of scan registers serially coupled between the test input pin and the test output pin. The scan registers in the set of scan registers are clocked by a clock signal. At least one input register is coupled between the test input pin and a first scan register of the scan chain. The at least one input register is clocked by an inverted replica of the clock signal.

A clock self-testing method and circuit. The clock self-testing method includes introducing a first clock signal and a second clock signal, counting cycles of the first clock signal and the second clock signal respectively beginning at the same moment, and if one of the number of cycles of the first clock signal being counted and the number of cycles of the second clock signal being counted is equal to N, determining whether the remained number of cycles is in a count range from M to N. If the remained number of cycles is out of the count range from M to N, the first clock signal and the second clock signal have errors.

An Integrated Circuit (IC) includes a storage element and control circuitry. The control circuitry is configured to select, responsively to a scan-enable control, between a functional-data input and a scan-data input to serve as an input to the storage element, to selectively disable toggling of an output of the storage element, responsively to a clock-enable control, by gating a clock signal provided to the storage element, and, while the clock-enable control indicates that the output of the storage element is to be disabled from toggling, to select the input of the storage element to be the scan-data input.

Testing clock division circuitry includes generating pseudo random test pattern bits for scan chain logic in programmable clock division logic circuitry and divided clock counter circuitry. A shift clock is used to shift the test pattern bits into the scan chain logic. A capture clock signal is used in the programmable clock division logic during a non-test mode of operation. The shift clock is used to provide output shift bits from the scan chain logic to a multi-input shift register (MISR). Once all the output shift bits for the test pattern bits are provided to the MISR, a final test signature from the MISR is compared to an expected test signature to determine whether the programmable clock division logic circuitry and divided clock counter circuitry are free of faults.

A semiconductor device of the embodiment includes a plurality of scan chains, a shift clock control circuit, and a shift clock generation circuit. The plurality of scan chains each include a plurality of scan flip-flops. The shift clock control circuit outputs, to each of the plurality of scan chains, a control signal that non-inverts or inverts a scan clock signal. The shift clock generation circuit is provided to each of the plurality of scan flip-flops and generates a non-inverted scan clock signal or an inverted scan clock signal based on the control signal, the non-inverted scan clock signal being obtained by non-inverting the scan clock signal, the inverted scan clock signal being obtained by inverting the scan clock signal.

The disclosure describes a novel method and apparatus for improving the operation of a TAP architecture in a device through the use of Command signal inputs to the TAP architecture. In response to a Command signal input, the TAP architecture can perform streamlined and uninterrupted Update, Capture and Shift operation cycles to a target circuit in the device or streamlined and uninterrupted capture and shift operation cycles to a target circuit in the device. The Command signals can be input to the TAP architecture via the devices dedicated TMS or TDI inputs or via a separate CMD input to the device.

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.

This disclosure describes die test architectures that can be implemented in a first, middle and last die of a die stack. The die test architectures are mainly the same, but for the exceptions mentioned in this disclosure.

In one embodiment, a device comprises: a first die having disposed thereon a first plurality of latches wherein ones of the first plurality of latches are operatively connected to an adjacent one of the first plurality of latches; and a second die having disposed thereon a second plurality of latches wherein ones of the second plurality of latches are operatively connected to an adjacent one of the second plurality of latches. Each latch of the first plurality of latches on said first die corresponds to a latch in the second plurality of latches on said second die. Each set of corresponding latches are operatively connected. A scan path comprises a closed loop comprising each of said first and second plurality of latches. One of the second plurality of latches is operatively connected to another one of the second plurality of latches via an inverter.