An integrated circuit includes first to n.sup.th metal layers vertically stacked on a substrate, and a test circuit outputting a test result signal according to a characteristic of each of the first to n.sup.th metal layers. The test circuit includes first to n.sup.th test circuits for generating a plurality of clock signals. Each clock signal of the plurality of clock signal has a frequency according to a characteristic of a corresponding metal layer among the first to n.sup.th metal layers, and n is a natural number.

An integrated circuit includes first to n.sup.th metal layers vertically stacked on a substrate, and a test circuit outputting a test result signal according to a characteristic of each of the first to n.sup.th metal layers. The test circuit includes first to n.sup.th test circuits for generating a plurality of clock signals. Each clock signal of the plurality of clock signal has a frequency according to a characteristic of a corresponding metal layer among the first to n.sup.th metal layers, and n is a natural number.

The disclosure describes a novel method and apparatus for providing a shadow access port within a device. The shadow access port is accessed to perform operations in the device by reusing the TDI, TMS, TCK and TDO signals that are used to operate a test access port within the device. The presence and operation of the shadow access port is transparent to the presence and operation of the test access port. According to the disclosure, the shadow access port operates on the falling edge of the TCK signal while the test access port conventionally operates on the rising edge of the TCK signal.

The disclosure describes a novel method and apparatus for providing a shadow access port within a device. The shadow access port is accessed to perform operations in the device by reusing the TDI, TMS, TCK and TDO signals that are used to operate a test access port within the device. The presence and operation of the shadow access port is transparent to the presence and operation of the test access port. According to the disclosure, the shadow access port operates on the falling edge of the TCK signal while the test access port conventionally operates on the rising edge of the TCK signal.

Extra edges are added to a group of edges for use in decoding syndrome measurements of a surface code implemented using hybrid acoustic-electric qubits. The extra edges include two-dimensional cross-edges and three-dimensional space-time correlated edges that identify correlated errors arising from spurious photon dissipation processes of a multiplexed control circuit that leads to cross-talk between storage modes of a set of the mechanical resonators controlled by the given multiplexed control circuit. Additionally, error probabilities used for edge weighting incorporate error probabilities due to the spurious photon dissipation processes.

Extra edges are added to a group of edges for use in decoding syndrome measurements of a surface code implemented using hybrid acoustic-electric qubits. The extra edges include two-dimensional cross-edges and three-dimensional space-time correlated edges that identify correlated errors arising from spurious photon dissipation processes of a multiplexed control circuit that leads to cross-talk between storage modes of a set of the mechanical resonators controlled by the given multiplexed control circuit. Additionally, error probabilities used for edge weighting incorporate error probabilities due to the spurious photon dissipation processes.

A system is provided that includes a memory configured to store test patterns. A first lockstep core and a second lockstep core are configured to receive the same set of test patterns. First scan outputs are generated from the first lockstep core, and second scan outputs are generated from the second lockstep core during a reset of the first lockstep core and the second lockstep core. A comparator can be coupled to the first lockstep core and the second lockstep core and is configured to compare the first scan outputs to the second scan outputs. The first and second lockstep cores can be initialized to a similar state if the first and second scan outputs are the same. The first and second lockstep cores can comprise non-resettable flip flops.

A system is provided that includes a memory configured to store test patterns. A first lockstep core and a second lockstep core are configured to receive the same set of test patterns. First scan outputs are generated from the first lockstep core, and second scan outputs are generated from the second lockstep core during a reset of the first lockstep core and the second lockstep core. A comparator can be coupled to the first lockstep core and the second lockstep core and is configured to compare the first scan outputs to the second scan outputs. The first and second lockstep cores can be initialized to a similar state if the first and second scan outputs are the same. The first and second lockstep cores can comprise non-resettable flip flops.

A system for testing a circuit comprises scan chains, a controller configured to generate a bit-inverting signal based on child test pattern information, and bit-inverting circuitry coupled to the controller and configured to invert bits of a parent test pattern associated with a plurality of shift clock cycles based on the bit-inverting signal to generate a child test pattern during a shift operation. Here, the plurality of shift clock cycles for bit inverting occur every m shift clock cycles, and the child test pattern information comprises information of m and location of the plurality of shift clock cycles in the shift operation.

A system for testing a circuit comprises scan chains, a controller configured to generate a bit-inverting signal based on child test pattern information, and bit-inverting circuitry coupled to the controller and configured to invert bits of a parent test pattern associated with a plurality of shift clock cycles based on the bit-inverting signal to generate a child test pattern during a shift operation. Here, the plurality of shift clock cycles for bit inverting occur every m shift clock cycles, and the child test pattern information comprises information of m and location of the plurality of shift clock cycles in the shift operation.