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1859140000_Datasheet PDF

发帖时间:2021-06-15 02:55:12

It is a real benefit in team based designs for viewing the connectivity of your design blocks.

PCell caching in a multi-vendor custom IC design environment

Used in the design of analog and custom digital circuits, parameterized cells (PCells) are software scripts used to define physical layout based upon a prescribed set of variable parameters. PCells are the basic building blocks of custom IC design, offering a single programmable PCell in place of many different versions of a drawn cell. PCells can automate very sophisticated functions, maintain complex relationships, and can even interact with their environment. So you can imagine how disconcerting it is when your PCells disappear!

1859140000_Datasheet PDF

Historically, PCells have been written in proprietary scripting languages (such as Cadence SKILL) developed for each specific layout tool, which means that most PCells in existence today cannot be seen” by tools from other vendors because they do not have the software needed to evaluate the proprietary scripts.

Recently, the Interoperable PDK Library (IPL) Alliance (see www.IPLnow.com ) has initiated a standard for executing interoperable PCells which, coupled with the broad adoption of the OpenAccess interoperable database standard, is addressing the issue of disappearing PCells for new designs. But what about your legacy data? How do you protect your legacy PCells?

For a solution to that problem, a long-time programming methodology called caching” has been pressed into service. In computer programs, caching is used to store on disk the output from commonly used functions so that when executing a repeated instruction, the results may be obtained more quickly without having to reprocess the request. This same mechanism has been used by some companies to speed up the display of PCells in custom IC design environments and to make tool-specific PCells visible to multiple tools in the design flow.

1859140000_Datasheet PDF

The significance of these developments is clear: The implementation of interoperable PCells and PCell caching using an interoperable database can solve the Case of the Missing PCell.

Where did the PCell go? When an IC layout containing PCells (Fig. 1 ) is opened for viewing or editing by a layout editor, the tool evaluates each PCell script, generates the corresponding layout and holds it in memory. If any parameters are changed – either manually or by changing the parameters in the parameter attribute form – the layout editor will re-evaluate the PCell and change the layout accordingly. In many tools when the layout is saved or closed, only the PCell instance and the instance-specific parameters are written to disk, forcing the tool to re-evaluate the PCell each time it is opened.

1859140000_Datasheet PDF

Caching can be used to write the PCell layout to disk to make it available to any tool that is capable of reading the layout database of the originating tool. Without caching, the PCell layout will disappear when opened by other tools unless these tools can also execute the PCell script (Fig 2 ).

The compiled PCell code, ready for use by the custom IC design tool, is referred to as the PCell supermaster.” The supermaster contains no parameter values, just variables that are supplied during PCell evaluation through the Component Description Format (CDF).

The industry is predicting that data volumes could reach 2.7 exabytes per year [1] in 2010 and that volume could increase to between 20 and 90 exabytes in 2015 [2,3],   This expansion is driven by the consumer’s rapid adoption of smartphone and other datacentric terminals, such as datacards, e-readers, and laptops.  In order to support this type of data explosion, operators will need to take a multi-pronged approach: adding spectrum, improving radio link quality, and boost signal quality. To do all of that, they need to rethink the design of the RF front end.

First, they will deploy additional spectrum for data services, which is already occurring with network rollouts in the 700MHz bands in North America, the 2600MHz band in Europe, and 2300MHz band in China. This expansion will require the integration of more bands into mobile devices, which significantly increases the RF component count. Industry experts project that typical handsets will increase from three bands (today) to five bands over the next few years. In the fast-growing smartphone handset segment, the number of supported bands is expected to be even higher — in the range of 8 to 12 bands [4].

Second, operators will need to improve the radio link quality, which requires lower loss performance from the RF components and an optimized antenna interface.  The antenna is the component most affected by the addition of more frequency bands because it is very difficult to develop an antenna that covers two octaves yet maintains a form factor acceptable for the handset. The reality is, with an increase in frequency coverage, mobile handsets will require tunable antennas which are able to match the performance levels of previous generation phones.

Lastly, operators are reassigning spectrum previously reserved for 2/2.5G technology to next-generation wireless standards such as High-Speed Packet Access (HSPA), Evolved High-Speed Packet Access (HSPA+) and Long Term Evolution (LTE).  These newer technologies are able to support higher data rates and are more spectrally efficient, but they use more complicated modulation schemes which ultimately demands better signal quality from the terminals. In fact, to achieve the target peak data rates of LTE, a signal-to-noise ratio (SNR) of more than 30 dB is needed [5]. This is significant when compared to typical WCDMA systems which require a signal-to-noise ratio (SNR) of only a few dB.

RF front-end limitations The traditional RF front-end (RFFE) architecture shown in Figure 1 shows all of the signals passing through a single broadband signal path.  This architecture provided adequate performance for low-band-count solutions that were primarily used for voice services.  The challenges associated with this approach for high-band-count data-capable devices are discussed in more detail in the following sections.

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