Process Design Kits (PDKs)
Cell generators have become standard components in every Process Design Kit (PDK). PDKs are collections of design tools, libraries, and data files specific to a semiconductor manufacturing process. They are supplied for most semiconductor processes and are closely integrated with Electronic Design Automation (EDA) tools from leading companies. These cell generators are often referred to as “PCells,” which stands for parameterized cells.
Advanced Layout Generators
Today, IC design teams in large corporations develop layout generators based on cell generators present in PDKs. These layout generators can automatically create entire circuits or standard subcircuits. Such higher-level layout generators are sometimes called “module generators.”
In summary, the shift from manual layout to automated cell generators has revolutionized the design of integrated analog IC devices, significantly reducing design time and complexity while ensuring accuracy and adherence to technology-specific requirements.
How did the process of creating layouts for integrated analog IC devices change in the 1990s, and what are cell generators?
In the 1990s, there was a significant shift in the process of creating layouts for integrated analog IC devices. Cell generators became commonplace during this era. Cell generators are procedures or tools that take specific electrical or geometrical device properties as input parameters and automatically generate a correct layout cell tailored to a particular semiconductor technology.
Designers could directly call these cell generators from the circuit schematic, a process often referred to as “Pick and Place.” The cell generators would load sizing parameters from the device’s schematic symbol. These generators could handle not only electrical sizing parameters but also other layout attributes, such as the number, shape, and location of contact pins. They could also handle tasks like splitting devices into smaller subdevices, such as folding a FET (Field-Effect Transistor). The subdevices generated by these tools were then appropriately placed and routed concerning one another.
What are some of the key features of cell generators?
Cell generators are a crucial component of modern semiconductor design for several reasons:
Parameterization: Cell generators are parameterized, meaning they can create layout cells based on specific input parameters. This allows for flexibility in designing integrated analog IC devices tailored to different technology requirements.
Automation: They automate the layout creation process, reducing the need for labor-intensive manual polygon pushing. This significantly speeds up the design process and reduces the potential for human errors.
Integration: Cell generators are typically integrated into the semiconductor process design kit (PDK). They work closely with electronic design automation (EDA) tools, making them an integral part of the design flow.
Standardization: They provide standardized procedures for generating layouts, making it easier for design teams to work with semiconductor processes supplied by different foundries.
What are higher-level layout generators, and why are they becoming more common in modern IC design?
Higher-level layout generators, sometimes referred to as module generators, are tools used in modern integrated circuit (IC) design. These generators are capable of automatically creating entire circuits or standard subcircuits. They build upon the functionality of cell generators and are developed by IC design teams in large corporations.
Higher-level layout generators are becoming more common in modern IC design for several reasons:
Efficiency: They significantly improve the efficiency of the design process by automating the creation of larger sections of a circuit or even entire circuits.
Consistency: They ensure a high level of layout consistency across different parts of a design, reducing the risk of errors and improving overall design quality.
Time Savings: These generators save considerable time in the layout phase, enabling designers to focus more on the high-level aspects of circuit design.
Integration: They seamlessly integrate with other EDA tools, further streamlining the design flow.
Overall, higher-level layout generators are a response to the growing complexity of modern IC designs and the need for efficient, error-free design processes.