Methods, apparatus, systems and articles of manufacture are disclosed to simulate metastability for circuit design verification. An example apparatus includes an input handler to receive circuit design data indicative of a circuit design, a circuit modeler to generate a simulation model based on the circuit design data, a simulator to simulate operation of the circuit design based on the simulation model, a metastability injector to insert metastability logic into the simulation model during the simulation, and a metastability controller to control the metastability logic during the simulation.

Some aspects of this disclosure are directed to implementing formal gated clock conversion for field programmable gate array (FPGA) synthesis. For example, some aspects of this disclosure relate to a method, including receiving network representation of a circuit design, determining a gated clock function corresponding to a target component of the network representation, and constructing an edge function based at least in part on the gated clock function. The method further includes performing a minimization of the edge function, and in response to a determination that the minimization of the edge function comprises a first term and a second term, providing a clock enable signal to the target component based on the first term, and providing a clock signal to the target component based on the second term.

A clock sweeping system includes multiple delay elements and a selection circuit. The delay elements are configured to generate multiple delayed clock signals. Each delay element is configured to receive an input signal and delay the input signal to generate a corresponding first delayed clock signal. The input signal is one of a first clock signal, a second clock signal, and a corresponding output signal generated by a previous delay element. The selection circuit is configured to select and output, based on a first select signal for a plurality of times, a corresponding second delayed clock signal as a first output clock signal. The selection circuit is further configured to select and output, based on a second select signal, one of the first and second clock signals as a second output clock signal. The first output clock signal is asynchronous with respect to the second output clock signal.

A layout method of a semiconductor device is disposed. The layout method includes: disposing a first metal strip directed to a first clock signal and disposing a first block strip parallel with the first metal strip, wherein the first block strip is indicative of a first blockage which prevents a routing tool from placing another metal strip on the location of the first block strip.

Methods, apparatus, systems and articles of manufacture are disclosed to simulate metastability for circuit design verification. An example apparatus includes an input handler to receive circuit design data indicative of a circuit design, a circuit modeler to generate a simulation model based on the circuit design data, a simulator to simulate operation of the circuit design based on the simulation model, a metastability injector to insert metastability logic into the simulation model during the simulation, and a metastability controller to control the metastability logic during the simulation.

An integrated circuit includes a clocking transistor, a first enabling transistor, a second enabling transistor, a branch-one transistor, a branch-two transistor, and a clock gating circuit. The first enabling transistor is coupled between the clocking transistor and a first node. The second enabling transistor is coupled between the clocking transistor and a second node. The branch-one transistor is coupled between a first power supply and the first node. The gate terminal of the branch-one transistor is electrically connected to the second node. The branch-two transistor is coupled between the first power supply and the second node. The gate terminal of the branch-two transistor is electrically connected to the first node. The clock gating circuit for generating a gated clock signal receives a latch output signal which is latched to a logic level of either a first node signal or a second node signal.

Some aspects of this disclosure are directed to implementing formal gated clock conversion for field programmable gate array (FPGA) synthesis. For example, some aspects of this disclosure relate to a method, including receiving network representation of a circuit design, determining a gated clock function corresponding to a target component of the network representation, and constructing an edge function based at least in part on the gated clock function. The method further includes performing a minimization of the edge function, and in response to a determination that the minimization of the edge function comprises a first term and a second term, providing a clock enable signal to the target component based on the first term, and providing a clock signal to the target component based on the second term.

Embodiments of the present technology provide a synchronous device. The synchronous device provides a first latch configured to store a data input signal during a first state of a first clock signal and a slack guard circuit. The slack guard circuit provides a delay element coupled to the first latch and configured to generate a delayed data signal, a gated-input cell coupled to the delay element and configured to propagate the delayed data signal during the first state of the first clock signal, and a comparator coupled to the first latch and the gated-input cell.

A simulation method includes a process of calculating a transient charge density q.sub.T of trapped charges after applying a voltage between a gate electrode and a semiconductor layer of a transistor, the charge density q.sub.T being calculated with a time variance of the charge density q.sub.T being expressed by a function obtained by superimposing multiple exponential functions having mutually different time constants.

Various embodiments provide for clock network generation for a circuit design using a negative-edge integrated clock gate (ICG). According to some embodiments, a clock network with one or more negative-edge ICGs is generated, after a topology of the clock network is defined, by applying a positive-edge ICG-to-negative-edge ICG transform to one or more nodes of the clock network that comprise a positive-edge ICG. Additionally, according to some embodiments, a clock network is generated bottom-up (from the clock sinks to the root clock signal source) using one or more negative-edge ICGs.