Abstract:
A system, apparatus and computer-implemented method for manipulating a parameterized cell device into a custom layout design. The method begins by receiving at least one parameterized cell representing a physical circuit from, for example, a database or configuration file. The parameterized cell has a plurality of configurable attributes. The method continues by adjusting one of the configurable attributes of the parameterized cell according to a capability associated with the one attribute. The attributes may include one or more of a parameter mapping capability, a port mapping capability, an abutment capability, a directional extension capability, a channel width capability, and a boundary layer capability. The method then calculates a new configuration for the parameterized cell based upon the adjustment, and applies the new configuration for the parameterized cell to a layout of the represented physical circuit.

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to systems, apparatus and methods in the field of electronic design automation and, more particularly, for improved apparatus, systems and methods of manipulating parameterized cell devices in a custom layout design. 
     BACKGROUND OF THE INVENTION 
     Electronic design automation (EDA) is a general term used to describe computer-based design tools that assist an engineer or designer in their design tasks. EDA tools are especially useful in the integrated circuit (IC) design field. The improvement of EDA tools for IC design work has enabled a corresponding increase in speed to market for electronic products and facilitated a greater level of sophisticated interoperability between systems used by disparate designers and manufacturers. 
     EDA tools often involve circuit schematic capture, design verification and circuit layout for IC circuit design in the analog, digital, mixed signal, and custom circuit devices fields. With the layout aspect of EDA work, IC designers continue to strive towards more efficient use of a device&#39;s physical space. Manual and automated layout tools within conventional EDA tools commonly assist IC designers in this manner. When attempting to maximize circuit density within design rule constraints, IC designers often need to manipulate the layout of a device design, which can be onerous and introduce errors leading to performance issues or other design rule violations. Thus, particular attention is paid to layout within EDA tools. 
     Parameterized cells (PCells) provide an advanced level of EDA to help better address layout tasks faced by an IC designer. PCells are commonly known within the EDA and IC design fields to allow for changing the size, shape or contents of each cell instance, without changing the original cell. As such, similar to concepts of object-oriented programming, PCells introduce an improved level of abstraction to the component levels of IC design. This helps accelerate the layout task facing an IC designer and helps avoid or reduce design rule verification errors by simplifying complex shapes and devices that may be generated and edited within an EDA tool. However, there remains a need for an improved way to use and manipulate PCells within an EDA tool that results in an efficient and custom device layout design. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with aspects of the present invention, a system, apparatus and computer-implemented method is provided for manipulating a parameterized cell device into a custom layout design. In one aspect, a method begins by receiving at least one parameterized cell representing a physical circuit from, for example, a database or configuration file. The parameterized cell has a plurality of configurable attributes. The method continues by adjusting one of the configurable attributes of the parameterized cell according to a capability associated with the one attribute. The attributes may include one or more of a parameter mapping capability, a port mapping capability, an abutment capability, a directional extension capability, a channel width capability, and a boundary layer capability. The method then calculates a new configuration for the parameterized cell based upon the adjustment, and applies the new configuration for the parameterized cell to a layout of the represented physical circuit. 
     In another aspect, a method is provided for manipulating a parameterized cell. The method begins by receiving a parameterized cell representing an instance of a physical circuit where the parameterized cell has a plurality of configurable attributes. The parameterized cell is displayed as one or more symbols on a display in an initial configuration. The method continues by manipulating at least one of the symbols to adjust one of the configurable attributes of the parameterized cell according to a capability associated with the one attribute, where the manipulated symbols forming a new configuration for the parameterized cell. The method then displays the new configuration for the parameterized cell on the display. 
     In yet another aspect, a method is provided for manipulating a parameterized cell that starts by receiving a layout representing an instance of a physical circuit and then converting the layout into one or more symbols associated with the parameterized cell, which has a plurality of configurable attributes. The method continues by displaying the parameterized cell as one or more symbols on a display, the symbols being in an initial configuration. Then, the method manipulates at least one of the symbols to adjust one of the configurable attributes of the parameterized cell according to a capability associated with the one attribute, the manipulated symbols forming a new configuration for the parameterized cell. The method displays the new configuration for the parameterized cell on the display and generates a new layout associated with the new configuration for the parameterized cell. 
     In a final aspect, an apparatus is described for manipulating a parameterized cell. The apparatus comprises a processor, a video display coupled to the processor, an input device coupled to the processor, and a memory storage coupled to the processor. The memory storage maintains, at least. a circuit schematic database, a device database associated with the parameterized cell, and a symbol placement editor software module. When the symbol placement editor software module is executed, the processor is further configured to read the parameterized cell from the device database, the parameterized cell representing an instance of a physical circuit; the parameterized cell having a plurality of configurable attributes. The processor can control the display of the parameterized cell as one or more symbols on the video display in an initial configuration. The processor can also adjust one of the configurable attributes of the parameterized cell according to a capability associated with the one attribute, the adjustment being in response to an input received by the input device, the manipulated symbols forming a new configuration for the parameterized cell. Further, the processor can control the display of the parameterized cell on the video display in the new configuration for the parameterized cell. 
     Additional advantages of this and other aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exemplary device creation flow diagram in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an exemplary circuit. 
         FIG. 3  is a diagramatic instance of an exemplary PCell associated with the exemplary circuit of  FIG. 2 . 
         FIG. 4  is a layout of the exemplary circuit of  FIG. 2 . 
         FIG. 5A  is a diagram illustrating a parameter mapping capability associated with the exemplary circuit of  FIG. 2  in accordance with an embodiment of the present invention. 
         FIG. 5B  is a diagram illustrating another example of a parameter mapping capability in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram illustrating a port mapping capability associated with the exemplary circuit of  FIG. 2  in accordance with an embodiment of the present invention. 
         FIG. 7  is a diagram illustrating an abutment capability associated with the exemplary circuit of  FIG. 2  in accordance with an embodiment of the present invention. 
         FIG. 8  is a diagram illustrating a left/right 00 extend capability associated with the exemplary circuit of  FIG. 2  in accordance with an embodiment of the present invention. 
         FIG. 9  is a listing representing the contents of an exemplary configuration file in accordance with an embodiment of the present invention. 
         FIG. 10  is a diagram illustrating a result of PCell manipulation treatment of an exemplary device using parameter mapping and port mapping capabilities in accordance with an embodiment of the present invention. 
         FIG. 11  is a diagram illustrating a result of PCell manipulation treatment of an exemplary device using parameter mapping, port mapping and abutment capabilities in accordance with an embodiment of the present invention. 
         FIG. 12  is a layout of the result shown in  FIG. 11  in accordance with an embodiment of the present invention. 
         FIG. 13  is a diagram illustrating a result of PCell manipulation treatment of an exemplary device using an alternative finger number in accordance with an embodiment of the present invention. 
         FIG. 14  is a layout of the result shown in  FIG. 13  with an alternative channel width automatically calculated from the alternative finger number in  FIG. 13  in accordance with an embodiment of the present invention. 
         FIGS. 15 and 16  illustrate an example embodiment with a dummy device added having a customized channel width in accordance with an embodiment of the present invention. 
         FIG. 17  is a schematic diagram of another exemplary circuit. 
         FIG. 18  is a diagramatic instance of exemplary PCells associated with the exemplary circuit of  FIG. 17 . 
         FIG. 19  is a layout of the exemplary circuit of  FIG. 17 . 
         FIG. 20  is an exemplary diagram illustrating an alignment manipulation of select PCells associated with the exemplary circuit of  FIG. 17 . 
         FIG. 21  is a layout of the result shown in  FIG. 20  in accordance with an embodiment of the present invention. 
         FIG. 22  is an exemplary diagram illustrating fold/merge manipulation of select PCells associated with the exemplary circuit of  FIG. 17 . 
         FIG. 23  is a layout of the result shown in  FIG. 22  in accordance with an embodiment of the present invention. 
         FIG. 24  is an exemplary computer-implemented operating environment for an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to exemplary embodiments. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     In general, embodiments of an apparatus and method for manipulating parameterized cells (PCells) in a custom layout design are described herein.  FIG. 24  is a general diagram of a computer system on which the software modules and applications shown in  FIG. 1  may execute. Exemplary apparatus, circuits, and systems used to help describe aspects of embodiments of the invention appear in  FIGS. 2 and 17 . The remaining Figures illustrate various aspects of how PCells may be advantageously manipulated in the context of exemplary circuits in accordance with principles of the present invention. 
     Referring first to  FIG. 24 , an exemplary computer-implemented operating environment is illustrated that is suitable for practicing methods and implementing an apparatus and systems consistent with principles and aspects of the present invention. Computer system  2400  of  FIG. 24  is shown connected to a network  2470 , such as a Local Area Network, Wide Area Network, or the Internet. Computer system  2400  contains a central processing unit (CPU)  2410 , a memory storage device called main memory  2440  (e.g., RAM, ROM, or a combination of both), a secondary memory storage device  2420 , an input device  2460  (e.g., a keyboard, mouse, tablet, touch pad interface, etc.), and a video display  2450 , each of which are electronically coupled to the other parts of computer system  2400 . Computer system  2400  also includes a data communications interface  2430 , which is also electronically coupled to the other parts of the computer system  2400  and facilitates data communications with network  2470  and other computer systems (not shown) or network storage devices (not shown). In an exemplary embodiment consistent with the present invention, computer system  2400  may be implemented as a single general purpose computer. However, those skilled in the art will appreciate that computer system  2400  may also be implemented in a client/server configuration, a cloud computing configuration, or other multi-processor or massively parallel computing implementations that take advantage of alternative hardware and network architectures useful for EDA use. 
     Within computer system  2400 , main memory  2440  contains an operating system  128 , applications (such as circuit design software  124 ), software libraries (such as circuit libraries  126 ), and user data files (such as files  122  created using circuit design software  124  to represent a particular circuit or groups of circuits). Embodiments of the present invention may be implemented as computer software (such as applications, software libraries or user files) residing on computer-readable media, which when read and executed by a conventional computer, causes the computer to function as part of a system, such as an IC design and layout system, executing an improved method in accordance with the invention for manipulating parameterized cells in a custom layout design. Suitable computer-readable media includes, but is not limited to, main memory  2440  or secondary storage memory  2420  (e.g., hard drives, compact disks, floppy disks, magneto-optical disks, DVD media, network storage drives, flash memory device and other electronic articles having computer memory). 
     In the context of such an exemplary computer system,  FIG. 1  illustrates an exemplary device creation flow diagram in terms of software modules within circuit design software  124 /circuit libraries  128  and exemplary files stored as user data files  122  in accordance with an embodiment of the present invention. In one embodiment, these software modules (implemented as software  124 , libraries  126  and/or user data files  126 ) include the following operationally-linked modules:
         Circuit Schematic  150 : A design circuit schematic database, which may be implemented as an OpenAccess (OA) compliant database facilitating interoperability between OA EDA vendor tools.   Device Database  155 : A database for any parameterized device. Exemplary embodiments of such parameterized devices include, but are not limited to, a MCell™ (also referred to as a Magic Cell™), Tel PCell, PyCell™, UDD (user-defined devices), and/or other OA implementations of a PCell. The Device Database  155  may comprise a library of PCells as part of a process design kit (PDK).   Configuration File(s)  160 : A file used to provide information regarding a PCell (e.g., PyCell, Tel PCell, UDD, etc.). Because some devices (especially OA PCells) are isolated modules that may not pass any information to a Device Interface (described below), this file is used to help the Device Interface to understand particular PCells beyond that or in addition to what is stored in the Device Database.   Device Interface  165 : A software interface module between features (e.g., floor planning and MDC/SDC) and device related information (such as information stored in the Device Database  155  and Configuration Files  160 ). The Device Interface  165  provides programmatic access to the device related stored information and helps the other features of circuit design software  124  (such as MDC/SDC  170  or Circuit Layout  175 ) understand device behavior when editing the design and creating proper circuit layouts.   MDC/SDC  170 : A symbol placement editor software tool using a match device creator (MDC) and/or a stick diagram compiler (SDC).   Circuit Layout  175 : A layout database. In one embodiment, the Circuit Layout  175  may be implemented with an OA compliant Laker™ Custom Layout System from SpringSoft, Inc.       

     In the context of the above referenced computer hardware ( FIG. 24 ) and software operating environment ( FIG. 1 ), several examples will be described in accordance with embodiments and principles of the present invention.  FIG. 2  provides a schematic diagram of an exemplary circuit  200  having a differential pair of transistors M 3  and M 4 . As shown in  FIG. 2 , transistors M 3  (element  205 ) and M 4  (element  210 ) are graphically depicted connected and coupled in a differential configuration. One skilled in the art will appreciate that the accompanying text shown for each transistor in  FIG. 2 &#39;s schematic diagram provides information for each of the respective elements and will depend upon the particular schematic entry tool and databases used as part of the EDA system. 
     In an embodiment using MDC, the PCell associated with the exemplary differential pair of  FIG. 2  is treated as an instance and the result in MDC is illustrated in  FIG. 3  as two symbols  305 ,  310 . The realized layout result of the exemplary differential pair of  FIG. 2  is illustrated in  FIG. 4  as two layout structures  405  and  410 . 
     In an embodiment of the present invention, a device (e.g., the exemplary differential pair of  FIG. 2 ) is associated with a PCell and may be displayed with one or more of the following capabilities: 
     1. Parameter mapping (illustrated in  FIG. 5A ) where the “Scale” is optional; 
     2. Port mapping (illustrated in  FIG. 6 ), which is optional; 
     3. Abutment (illustrated in  FIG. 7  where elements  705  and  710  may be manipulated to abut each other, which results in element  715 ); 
     4. Left/right oxide diffusion (OD) extension with parameter control (illustrated in  FIG. 8  where element  805  has an oxide diffusion that may be extended accordingly); 
     5. Min/max channel width/length; and 
     6. Boundary layer. 
     With reference to  FIG. 5A , the parameters, each of which are a type of configurable attribute or parameter, in the exemplary illustrated mapping include the following:
         W: total channel width of MOS device;   WF: finger number of MOS device;   L: channel length of MOS device;   NF: finger number of MOS device;   LOD_Ext: parameter that affects the left most OD width of MOS device; and   ROD Ext: parameter that affects the right most OD width of MOS       

     Those skilled in the art will appreciate that other parameters may be included in such a mapping. For example,  FIG. 5B  illustrates another exemplary mapping of parameters, which includes similar parameters as shown in  FIG. 5A  but also includes an SD_Swap parameter (i.e., a parameter that swaps the logic information (net, port) on the source and drain pins). 
     The device can be displayed with such capabilities as one or more symbols in MDC, SDC, and symbol placement editor. One skilled in the art will appreciate that MDC/SDC  170  typically starts from a schematic design. That is, the user first designs a circuit (such as circuit  200 ) in a schematic editor, and then uses MDC/SDC  170  to implement the designed circuit in an exemplary layout. In one embodiment, MOS symbols representing such conventionally known circuit elements in the schematic are imported to MDC/SDC  170 , from which the user may then manipulate the symbols in MDC/SDC  170  and generate a revised configuration of the exemplary layout. 
     However, in another embodiment, the user may start from an existing layout and convert the layout into one or more symbols, and then manipulate those symbols in a symbol-aware layout editor. For example, the user may start with an existing layout that includes PCell instances. Using the mapping file, those PCell instances may be represented as symbols. A layout editor that is capable of handling such symbols may be used to manipulate those PCell instances in a way similar to MDC/SDC  170 . With the symbols being abstract views of an exemplary layout, editing in symbol mode saves the user from being cluttered with the increasing details of the actual full layout. 
       FIG. 9  is an exemplary listing representing the contents of an exemplary configuration file, which defines an appropriate parameter mapping scheme for the particular device related to the configuration file. As displayed, such as seen in the examples shown in the Figures associated with this description, these symbol mode editors can honor the particular device geometries and display the related symbol size for the device in the editor. In some embodiments, these mapping schemes are also bi-directional. As such, the particular device may be generated from the symbol editor to the layout or extracted from the layout to the symbol editor. 
     In one embodiment using the above capabilities 1 &amp; 2, an exemplary device can be treated as MOS in MDC, which is shown in  FIG. 10 . In another embodiment using the above capabilities 1, 2 &amp; 3, an exemplary device can be treated as MOS in MDC with OD sharing as illustrated in the result diagram of  FIG. 11  and in the layout diagram of  FIG. 12 . 
     Using an embodiment of the present invention, a user may also edit the device in MDC to manipulate the PCell to an alternative number of device elements (which is commonly referred to as “number of fingers” and more generally referred to as a “number of devices”.) For example, the PCell for the exemplary device shown in  FIG. 11  may be manipulated from having a finger number of two to a finger number of four as shown in  FIG. 13 . Consequently, the channel width of the PCell alters automatically from 2.4 u as shown in  FIG. 12  to 1.2 u as shown in  FIG. 14 . In an embodiment of the invention, such manipulation may be accomplished automatically when realizing or generating the resulting layout. If the finger number is large enough that the resulting channel width is smaller than the minimum channel width, the MDC module may block the layout realization in accordance with principles of the present invention. Additionally, as shown in embodiments illustrated in  FIGS. 15 and 16 , one or more dummy devices (shown as “voids!” structures) may be added to the PCell in MDC and the channel length of the dummy may be customized by the user. A minimum channel length may be defined in the related device information associated with the PCell for the device (e.g., in a configuration file or other mapping file). 
     The same editing scheme may be used in SDC.  FIG. 17  illustrates an embodiment with another exemplary schematic circuit comprising various devices, such as devices (generally referred to as structures) MO/M 1 /M 5  in the schematic of  FIG. 17 .  FIG. 18  is a diagram of the symbol mode placement of these exemplary devices in the circuit of  FIG. 17  and the realized layout model of these devices is shown in  FIG. 19 . 
     In an embodiment shown in  FIG. 20 , the PCell may be manipulated by aligning M 5 . 1  with M 0  and M 5 . 2  with M 1 . 2 . The realized layout of such a result is shown in  FIG. 21 . As indicated in a comparison of the exemplary layout results shown in  FIGS. 19 and 21 , the spacing between M 5 . 1  and M 5 . 2  is different. In more detail, an exemplary method of the present invention manipulates the alignment via adjustable capabilities of the related PCell. The exemplary method, implemented with executable code of the circuit design software that advantageously manipulates the PCell (via a transformation of PCell information representing the alternative exemplary circuit of  FIG. 17 ) generally comprises the following steps:
         1. Calculate the pitch of M 0  and M 1 . 2 ;   2. Calculate the pitch of M 5 . 1  and M 5 . 2 ;   3. Calculate the difference between the two pitches; and   4. Apply the difference to the ROD ext parameter to enlarge the right side OD extension of M 5 . 1 .       

     These manipulations transform the PCell data representing a physical circuit, which results in layout changes. 
     In other embodiments of the present invention, the system provides the capability to “Fold” (increasing the number of fingers) or “Merge” (reducing the number of fingers) any device, such as a gate. To manipulate the “Fold” capability with regard to the M 5 . 2  structure shown in  FIG. 18 , the result will be the M 5 . 2 . 1  and M 5 . 2 . 2  structures as shown in the embodiment illustrated in  FIG. 22 . In that embodiment, the channel width of M 5 . 2 . 1  and M 5 . 2 . 2  in  FIG. 22  are half of the M 5 . 2  structures shown in  FIG. 18 . In another embodiment, to manipulate the “Merge” capability with regard to the M 1 . 1  and M 1 . 2  structures shown in  FIG. 18 , the result will be the M 1 . 1  structure in  FIG. 22  where the channel width of M 1 . 1  in  FIG. 22  will be the sum of M 1 . 1  and M 1 . 2  in  FIG. 18 . The layout result in such an embodiment is illustrated in  FIG. 23 . 
     While the above described embodiments explain the principles of the present invention in terms of active structures of one or more devices (e.g., transistors), embodiments of the invention may also be applied to other types of devices, such as resistor devices and capacitor devices. For example, in an alternative embodiment, the mapping scheme may be substantially the same as those described above with mapping parameters such as “width”, “length”, “value”, and the equations of resistor and capacitor value. Configuration files, such as the example illustrated in  FIG. 9 , may store such mapping parameters. Additionally, the editing commands in MDC for resistor and capacitor devices may be the same as with a MOS device. Resistor and capacitor device PCells may also support more advanced editing commands that provide the capability to arrange the different combinations of parallel and serial units to archive a better match pattern. 
     At least some portions of exemplary embodiments of the systems, apparatus and methods outlined above may used in association with portions of other exemplary embodiments. Moreover, at least some of the exemplary embodiments disclosed herein may be used independently from one another and/or in combination with one another and may have applications to devices and methods not disclosed herein. It will be apparent to those skilled in the art that various modifications and variations can be made to the structures and methodologies described herein. Thus, it should be understood that the invention is not limited to the subject matter discussed in the description. Rather, the present invention is intended to cover modifications and variations.