Apache License 2.0

技术解读

以下内容由 GitRead 中文社区 编辑团队基于项目 README 与官方资料整理, 结合中文开发者的常见使用场景补充技术选型建议。具体以项目官方文档为准。

深度分析:Google SkyWater PDK 项目

项目背景与痛点

在芯片设计与制造的流程中,一个至关重要的环节是使用 Process Design Kit (PDK),它使得集成电路设计工程师能够在特定的制造工艺下设计芯片。而 SkyWater Technology Foundry 提供的 130nm 工艺节点是较为成熟的工艺之一,但其 PDK 的使用文档和学习曲线相对较陡峭。

Google 所维护的 google/skywater-pdk 项目,旨在通过开源的方式提供一套 SkyWater 130nm 工艺节点的 PDK。通过此项目,开发者能够更加便捷地进行电路设计,加快原型设计与制造周期,降低开发门槛,尤其为开源硬件和研究项目带来极大的便利。

核心技术揭秘

google/skywater-pdk 项目的核心设计思想在于,它提供了一系列的工具和库文件,使设计者能够针对 SkyWater 的 130nm 工艺节点进行设计。其中涵盖了技术文件(如层定义、导电率、击穿电压等参数)、模拟模型(如晶体管、二极管等)和设计规则(例如最小布线宽度、最小间距等),这些都是进行设计时必不可少的信息。

技术架构展示

以下 Mermaid 图展示了 google/skywater-pdk 项目的核心组件以及数据流过程:

graph TD A[用户定制化设计] --> B[PDK 文件库] B --> C{"实现功能"} C -->|"逻辑综合与布局"| D[布局布线工具] C -->|"设计规则检查"| E[DRC 工具] D --> F[设计验证] E --> F F --> G[电路仿真实验] G --> H[制造文件输出] H --> I[生产数据交付]

设计者可以通过定制化设计,利用 PDK 提供的文件库,实现具体的功能。这些功能通过布局布线工具及设计规则检查工具进行验证。最终,实现详细的设计验证并输出制造文件,交付至生产线进行生产。

功能亮点与差异

与市面上的其他 PDK 对比,google/skywater-pdk 拥有以下优势:

  1. 开放源代码:提供了所有技术文件与库文件的开放源代码,社区维护,可以防止由于供应商单方面原因而出现的技术封锁。
  2. 多层次模块设计:针对不同的设计需求,提供了丰富的设计模块与参数可供选择,满足多变的设计需求。
  3. 完整的工具链支持:通过与布线工具及设计规则检查工具对接,确保设计的合法性与实用性。
  4. 丰富的社区支持:由于社区共同维护,有相对丰富的文档和专项支持资源,为设计者在遇到问题时提供即时的解决方案。

应用场景与落地建议

在实际的业务场景中,google/skywater-pdk 项目适用于多种具有 IC 设计需求的场景,包括但不限于开源硬件、研究项目以及小型创业公司的定制化设计。然而,在利用该项目时需注意以下几点:

  • 完全理解 PDK 参数:需要对提供的技术文档有深入的理解,尤其是工艺术数与设计规则,避免设计失误。
  • 严格按照工具链操作:在设计过程中,确保所有操作均满足工具链的要求,减少生产的不确定因素。
  • 密切关注版本更新:由于项目为开源项目,时常会有更新与改进,请密切关注更新信息。

综合评价

  • 优点:
    • 完全公开的技术文件库,反封锁性强。
    • 多层次的功能模块,适用性广。
    • 社区支持丰富,开源生态活跃。
  • 缺点:
    • 与商业 PDK 相比,某些细分性能指标可能有所差距。
    • 对初学者的技术门槛依然较高,需要基础的工艺知识与设计技巧。

通过全面的分析,google/skywater-pdk 项目为当今集成电路设计提供了开放且灵活的工具库,有助于加速设计流程,提高开发效率。

关于

GitHub 原始描述(英文)

Open source process design kit for usage with SkyWater Technology Foundry's 130nm node.

描述取自 GitHub 官方 API,保持仓库作者书写的原文。

简要分析

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语言占比

Makefile
Python

README

SkyWater Open Source PDK

… image:: https://img.shields.io/github/license/google/skywater-pdk :alt: GitHub license - Apache 2.0 :target: https://github.com/google/skywater-pdk

… image:: https://travis-ci.org/google/skywater-pdk.svg?branch=master :alt: Travis Badge - https://travis-ci.org/google/skywater-pdk :target: https://travis-ci.org/google/skywater-pdk

… image:: https://readthedocs.org/projects/skywater-pdk/badge/?version=latest&style=flat :alt: ReadTheDocs Badge - https://skywater-pdk.rtfd.io :target: https://skywater-pdk.rtfd.io

… image:: https://img.shields.io/github/v/tag/google/skywater-pdk?include_prereleases&sort=semver :alt: Latest GitHub tag (including pre-releases) :target: https://gitHub.com/google/skywater-pdk/commit/

… image:: https://img.shields.io/github/commits-since/google/skywater-pdk/v0.0.0 :alt: GitHub commits since latest release (v0.0.0) :target: https://gitHub.com/google/skywater-pdk/commit/

The SkyWater Open Source PDK is a collaboration between Google and SkyWater Technology Foundry to provide a fully open source Process Design Kit <https://en.wikipedia.org/wiki/Process_design_kit>_ and related resources, which can be used to create manufacturable designs at SkyWater’s facility.

As of May 2020, this repository is targeting the SKY130 process node. If the SKY130 process node release is successful then in the future more advanced technology nodes may become available.

The SkyWater Open Source PDK documentation can be found at https://skywater-pdk.rtfd.io.

… image:: docs/_static/skywater-pdk-logo.png :alt: Google + SkyWater Logo Image :align: center :target: https://github.com/google/skywater-pdk :width: 80%

… |current-status| replace:: Experimental Preview

Current Status – |current-status|

… current_status_text

Warning Google and SkyWater are currently treating the current content as an experimental preview / alpha release.

While the SKY130 process node and the PDK from which this open source release was derived have been used to create many designs that have been successfully manufactured commercially in significant quantities, the open source PDK is not intended to be used for production settings at this current time. It should be usable for doing test chips and initial design verification (but this is not guaranteed).

Google, SkyWater and our partners are currently doing internal validation and test designs, including silicon validation or the released data and plan to publish these results.

The PDK will be tagged with a production version when ready to do production design, see the “Versioning Information <docs/versioning.rst>_” section for a full description of the version numbering scheme.

To get notified about future new releases of the PDK, and other important news, please sign up on the skywater-pdk-announce mailing list <https://groups.google.com/forum/#!forum/skywater-pdk-announce>_ [join link <https://groups.google.com/forum/#!forum/skywater-pdk-announce/join>_].

See both the Known Issues <docs/known_issues.rst>_ section and the SkyWater PDK GitHub issue list <https://github.com/google/skywater-pdk/issues>_ to get more detailed information around currently known issues.

Resources

The latest SkyWater SKY130 PDK design resources can be viewed at the following locations:

  • On Github @ google/skywater-pdk <https://github.com/google/skywater-pdk>_
  • Google CodeSearch interface @ https://cs.opensource.google/skywater-pdk <https://cs.opensource.google/skywater-pdk>_
  • foss-eda-tools.googlesource.com/skywater-pdk <https://foss-eda-tools.googlesource.com/skywater-pdk/>_

SKY130 Process Node

The SKY130 is a mature 180nm-130nm hybrid technology originally developed internally by Cypress Semiconductor before being spun out into SkyWater Technology and made accessible to general industry. SkyWater and Google’s collaboration is now making this technology accessible to everyone!

The SKY130 Process node technology stack consists of;

  • Support for internal 1.8V with 5.0V I/Os (operable at 2.5V)
  • 1 level of local interconnect
  • 5 levels of metal
  • Is inductor-capable
  • Has high sheet rho poly resistor
  • Optional MiM capacitors
  • Includes SONOS shrunken cell
  • Supports 10V regulated supply
  • HV extended-drain NMOS and PMOS

The SKY130 Process Node_ is an extremely flexible offering, including many normally optional features as standard (features like the local interconnect, SONOS functionality, MiM capacitors, and more). This provides the designer with a wide range of flexibility in design choices.

If your needs extend beyond the standard included functionality in the SKY130 Process Node, please see Contacting SkyWater as they specializes in enabling production volume of process customization include the addition of specialized materials like Nb, Ge, V2O5, Carbon Nanotubes <https://www.skywatertechnology.com/technology/>. Google and SkyWater continuing to explore new options to be included in the SkyWater Open Source PDK and SKY130 Process Node_ that enable new innovative solutions to traditional design problems.

Typical usages of 130nm Process Nodes

The 130nm process <https://en.wikichip.org/wiki/130_nm_lithography_process>_ was first commercialized around the 2001-2002 time frame and is now primarily used in the area of research, small microcontroller development, and mixed signal embedded designs such as IoT devices.

A living Google document at https://j.mp/si130nm has been created to provide inspiration from what researchers, commercial entities and other groups have done with similar sized process nodes. As there are widely different constraints and possibilities from changes in both the manufacturing process and materials it is important not to assumed that the exact results found in the 130nm inspiration document <https://j.mp/si130nm>_ can be identically reproduced on the SKY130 Process Node_.

PDK Contents

The SkyWater Open Source PDK contains;

  • Comprehensive documentation around the design rules required to create manufacturable devices on the SKY130 Process Node.
  • EDA tooling support files for multiple open source and proprietary design flows.
  • Primitive cell libraries and models for creating analog designs.
  • Multiple standard digital cell libraries covering a range of different use cases.
  • Multiple documented examples of using the PDK (see below).

For more information see the PDK Contents section of the SkyWater SKY130 PDK <https://skywater-pdk.rtfd.io>_.

Using the SkyWater Open Source PDK

The SkyWater Open Source PDK aims to contain comprehensive documentation about using the design kit with multiple tools and design flows to enable many different types of ASIC creation.

  • [TODO #11] <https://github.com/google/skywater-pdk/issues/11>_ - Examples of using the PDK for digital design <https://skywater-pdk.rtfd.io>_.
  • [TODO #14] <https://github.com/google/skywater-pdk/issues/14>_ - Example of using the PDK to create a RISC-V SoC design using the OpenROAD ASIC tool flow <https://skywater-pdk.rtfd.io>_.
  • [TODO #12] <https://github.com/google/skywater-pdk/issues/12>_ - Examples of using the PDK for analog design <https://skywater-pdk.rtfd.io>_.
  • [TODO #13] <https://github.com/google/skywater-pdk/issues/13>_ - Examples of using the PDK with analog generators <https://skywater-pdk.rtfd.io>_ like FASoC <https://fasoc.engin.umich.edu/>_ and Berkeley Analog Generator (BAG) <https://github.com/bluecheetah/bag>_.

We are excited to see additions to this documentation around using this design kit with new tools and design flows. Please see the Contributing file <docs/contributing.rst>_ for information on how to do this.

To download or update to the ‘latest’ version of all standard cell libraries, and to regenerate the liberty files, clone this repository and run the following commands.

… code:: bash

Expect a large download! ~7GB at time of writing.

SUBMODULE_VERSION=latest make submodules -j3 || make submodules -j1

Regenerate liberty files

make timing

Support

Like many open source projects there are multiple ways to get support on the SkyWater Open Source PDK.

SkyWater has created a Market Partner Ecosystem to be able to provide support from design through back end package and test. If you are interested in getting additional support through the ASIC development process, reach out to SkyWater using the information in the Contacting SkyWater_ section below.

There is also a users mailing list <https://groups.google.com/forum/#!forum/skywater-pdk-users>_ [join link <https://groups.google.com/forum/#!forum/skywater-pdk-users/join>_] to allow like minded users of the PDK to provide support to each other.

Google does not provide external support for using the SkyWater Open Source PDK and is distributing this repository on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the license_ section for the full terms.

About SkyWater Technology Foundry

SkyWater is a solely U.S.-based and U.S.-owned, DoD-accredited, Trusted Foundry. Through its Technology Foundry model, SkyWater provides custom design and development services, design IP, and volume manufacturing for integrated circuits and micro devices. The Company’s world-class operations and unique processing capabilities enable mixed-signal CMOS, power, rad-hard and ROIC solutions. SkyWater’s Innovation Engineering Services empower development of superconducting and 3D ICs, along with carbon nanotube, photonic and MEMS devices. SkyWater serves customers in growing markets such as aerospace & defense, automotive, cloud & computing, consumer, industrial, IoT and medical. For more information, please visit: www.skywatertechnology.com/.

SkyWater is building from a long heritage in the microelectronics industry. The SkyWater facility was originally established by Minnesota based Control Data Corporation (CDC) in the 1980s. The CDC fab was acquired by Cypress Semiconductor in 1991. During the Cypress era, the facility was expanded and upgraded multiple times, keeping pace with Moore’s Law into the late 2000s and was known for being a US-based production facility that was competitive with Asian-based fabs. SkyWater spun-off from Cypress in 2017 with private equity backing from Minnesota based Oxbow Industries.

Contacting SkyWater

Requests for more information about SKY130 and other standard and customer foundry technologies can be emailed to [email protected] or submitted via this webform <https://www.skywatertechnology.com/contact/>_.

License

The SkyWater Open Source PDK is released under the Apache 2.0 license <https://github.com/google/skywater-pdk/blob/master/LICENSE>_.

The copyright details (which should also be found at the top of every file) are;

::

Copyright 2020 SkyWater PDK Authors

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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