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.

A semiconductor integrated circuit (IC) comprising a signal path combiner, comprising a plurality of input paths and an output path. The IC comprises a delay circuit having an input electrically connected to the output path, the delay circuit delaying an input signal by a variable delay time to output a delayed signal path. The IC may comprise a first storage circuit electrically connected to the output path and a second storage circuit electrically connected to the delayed signal path. The IC comprises a comparison circuit that compares outputs of the signal path combiner and the delayed signal, wherein the comparison circuit comprises a comparison output provided in a comparison data signal to at least one mitigation circuit.

The present disclosure provides a semiconductor wafer. The semiconductor wafer includes: a scribe line between a first row of dies and a second row of dies; and a benchmark circuit disposed adjacent to the scribe line and electrically coupled to a first conductive contact and a second conductive contact. The benchmark circuit includes a first device-under-test (DUT); a second DUT; a first switching circuit configured to selectively couple the first DUT and the second DUT to the first conductive contact; and a second switching circuit configured to selectively couple the first DUT and the second DUT to the second conductive contact.

An apparatus has a collection of ring oscillators. An instruction register block is configured to sequentially address and activate each ring oscillator in the collection of ring oscillators. A multiplexer with input lines is connected to each ring oscillator in the collection of ring oscillators and an output line. A pulse counter is connected to the output line of the multiplexer to count the number of oscillations of a selected ring oscillator within a selected time period to form a multiple bit frequency count output signal. A data shift register receives the multiple bit frequency count output signal and produces a serial frequency count output signal.

In certain aspects, a duty-cycle monitor includes a first oscillator, and a flop having a signal input, a clock input, and an output, wherein the signal input is coupled to an input of the duty-cycle monitor, and the clock input is coupled to the first oscillator. The duty-cycle monitor also includes a first counter having a count input, an enable input, and a count output, wherein the count input of the first counter is coupled to the first oscillator, and the enable input of the first counter is coupled to the output of the flop. The duty-cycle monitor also includes a second counter having a count input, an enable input, and a count output, wherein the count input of the second counter is coupled to the first oscillator, and the enable input of the second counter is coupled to the output of the flop.

The excitation of processing paths in a microelectronic circuit is organized by providing one or more pieces of input information to a decision-making software, and executing the decision-making software to decide, whether one or more of said processing paths of the microelectronic circuit are to be excited with test signals. Deciding that said processing paths are to be excited with said test signals results in proceeding to excite said one or more of said processing paths with said test signals and monitoring whether timing events occur on such one or more excited processing paths. A timing event is a change in a digital value at an input of a respective register circuit on an excited processing path, which change took place later than an allowable time limit defined by a triggering signal to said respective register circuit.

The present disclosure provides a process variation detection circuit and a process variation detection method. The process variation detection circuit is arranged in a chip and includes: a first ring oscillator, where a first number of auxiliary elements of a preset type are arranged between two adjacent inverters of the first ring oscillator; and a second ring oscillator, where a second number of auxiliary elements of a preset type are arranged between two adjacent inverters of the second ring oscillator, the second number is larger than the first number; wherein, a number of the inverter of the first ring oscillator is the same as a number of the inverter of the second ring oscillator; a type and a size of a transistor of the first ring oscillator are the same as a type and a size of a transistor of the second ring oscillator.

Aspects of the invention include a phase rotator, that is located at a built-in self-test (BIST) path of a receiver, receiving a clock signal from an on-chip clock. The phase rotator shifts the phases of the clock signal. The phase rotator transmits the shifted clock signal to a binary sequence generator, that is located at the receiver. The binary sequence generator outputs a binary sequence, where the binary sequence generator is driven by the shifted clock signal.

Circuits and methods involve an integrated circuit (IC) device, a plurality of application-specific sub-circuits, and a plurality of instances of a measuring circuit. The application-specific sub-circuits are disposed within respective areas of the IC device. Each instance of the measuring circuit is associated with one of the application-specific sub-circuits and is disposed within a respective one of the areas of the device. Each instance of the measuring circuit further includes a ring oscillator and a register for storage of a value indicative of an interval of time. Each instance of the measuring circuit is configured to measure passage of the interval of time based on a first clock signal, count oscillations of an output signal of the ring oscillator during the interval of time, and output a value indicating a number of oscillations counted during the interval of time.

Embodiments of the invention provide for integrated circuits for testing one or more transistors for process variation effects. According to an embodiment, the integrated circuit can include: a plurality of ring oscillator macro circuits, wherein each ring oscillator macro circuit includes two ring oscillators, a first multiplexer, and a first divide-by-two circuit; a multiplexer stage; a divide-by-two circuit stage; a second multiplexer; a second divide-by-two circuit; and frequency measurement circuit. According to another embodiment, the integrated circuit can include: a first shift register including a plurality of devices-under-test; a second shift register including a plurality of static latches; a first multiplexer configured to receive outputs from each of the plurality of DUTs; a second multiplexer configured to receive outputs from each of the plurality of static latches; and a comparator configured to compare an output from the first multiplexer with an output from the second multiplexer.