CV (connectivity verification)

Connectivity Verification (CV) is a process that is used to verify the connectivity of integrated circuits (ICs) in digital and mixed-signal systems. The goal of connectivity verification is to ensure that all the components of the IC are correctly connected and that there are no open or short circuits in the design.

The complexity of modern ICs makes manual verification impractical, if not impossible. Hence, automated tools are used to perform connectivity verification. These tools use a combination of design rule checks (DRCs), layout versus schematic (LVS) comparison, and other techniques to verify that the IC design meets the required specifications.

The process of connectivity verification starts with the IC design itself. The design is typically created using a hardware description language (HDL) such as Verilog or VHDL. The design is then translated into a layout, which is a two-dimensional representation of the IC. The layout is then optimized for manufacturability and converted into a set of mask layers that are used to fabricate the IC.

The first step in connectivity verification is DRC. DRC checks are used to ensure that the layout meets certain design rules. For example, DRCs may check that there is sufficient spacing between adjacent wires, that there are no overlapping layers, and that there are no short circuits or open circuits. DRCs are performed using specialized software that analyzes the mask layers of the IC.

The second step in connectivity verification is LVS. LVS compares the layout of the IC to the original design to ensure that they match. LVS checks are used to verify that the correct number of transistors are present in the layout, that the transistors are correctly connected, and that there are no floating nodes or unconnected components. LVS is performed using specialized software that compares the netlists of the original design and the layout.

After DRC and LVS checks are complete, any errors are reported to the designer. The designer can then make changes to the design or the layout to correct any errors. The design is then rechecked using DRC and LVS to ensure that the errors have been corrected.

In addition to DRC and LVS, other techniques are used to perform connectivity verification. For example, parasitic extraction is used to model the parasitic effects of the IC. Parasitic effects can cause signal delays and distortion, which can affect the performance of the IC. By modeling these effects, designers can optimize their designs to minimize their impact.

Another technique used in connectivity verification is simulation. Simulation involves running the IC design through a virtual model of the IC to verify its performance. Simulation can be used to verify the performance of individual components as well as the overall performance of the IC.

Connectivity verification is a critical step in the IC design process. Without proper connectivity verification, ICs can have defects that cause them to fail or perform poorly. Automated tools such as DRC, LVS, parasitic extraction, and simulation are used to ensure that IC designs meet the required specifications and are manufacturable.

In conclusion, connectivity verification is a process that is used to verify the connectivity of ICs in digital and mixed-signal systems. The process involves a combination of DRC, LVS, parasitic extraction, and simulation to ensure that the IC design meets the required specifications. Connectivity verification is a critical step in the IC design process, and automated tools are used to ensure that ICs are manufacturable and perform as expected.