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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallCPF and UPF describe much of the same low-power design intent, but they organize it differently. For a project, the useful comparison is not just which format can express power domains, isolation, retention, and switches; it is where library details come from, how power modes are tied to timing analysis, what simulation behavior is specified, and which format the project’s tools support. The comparison below reflects Dave Allen’s article published March 27, 2008—not a statement of current standard revisions or vendor compatibility.
What do CPF and UPF have in common?
Common Power Format (CPF) and Unified Power Format (UPF) are Tcl-based ways to capture power intent for low-power integrated-circuit and system-on-chip design and verification. Both can describe voltage and power domains, multiple supply nets, isolation, retention registers, always-on logic or paths, and power switches. In his 2008 comparison, Allen estimated that the formats shared about 90% of their concepts; that figure is his historical characterization, not a current measurement of format coverage or industry adoption. Electronic Design’s 2008 comparison is the source for the technical distinctions below.
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The overlap does not make the formats interchangeable line by line. Their syntax, command names, options, and organization differ, so translating a power-intent file may require understanding the design meaning and associated library information—not just substituting command names.
How do CPF and UPF differ?
| Design concern | CPF | UPF | Why it matters |
|---|---|---|---|
| Core power intent | Describes voltage and power domains, supply nets, isolation, retention, always-on paths, and power switches. | Describes the same broad categories of power intent. | Both can express many of the same design situations; syntax and information placement differ. |
| Library-cell details | Can define library elements such as level shifters and retention registers, including supply-pin and data-pin information. | In Allen’s examples, relies on another library format, such as Liberty, for related cell information. | Check where the project’s cell attributes are maintained and how the chosen tool reads them. |
| Power modes and timing analysis | Can associate library files and operating conditions with power modes, supporting static timing runs across voltage scenarios. | Allen’s examples do not show equivalent dedicated syntax for those associations. | This distinction may matter when power-mode-specific timing setup is part of the flow. |
| Simulation semantics | The examples emphasize other modeling capabilities rather than the UPF behaviors listed here. | Includes constructs for data corruption, checking retention-control sequences, and voltage resolution. | Review the simulation requirements and the semantics supported by the project’s tools; do not assume similarly named intent has identical behavior. |
| Tool ecosystem | Historically associated with Cadence and the Low Power Coalition. | Historically connected with Accellera and support announcements from multiple EDA vendors. | These are historical associations, not evidence of current product support. Verify actual support for the exact format revision and flow in use. |
How do they represent common low-power design situations?
Allen’s examples use recurring implementation problems to show the formats’ shared purpose. They are useful as a checklist of intent a project may need to capture, not as a claim that the syntax is directly portable between formats.
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- Two voltage domains: identify the domains and their supplies, then specify where level shifting is required for signals crossing between voltage levels.
- A switchable power domain: describe its supply and power-switch relationship, and specify isolation on outputs that could otherwise become invalid when the domain is off.
- Retention registers: identify the state that must be preserved and its save/restore or sleep controls.
- Power switches: capture the parent supply, switched child supply, and enable information.
The library-modeling distinction is especially relevant to level shifters and retention cells: CPF can carry certain cell and pin attributes in its own descriptions, while UPF’s examples expect related library information to come from a format such as Liberty. The intent may be similar, but the surrounding data dependencies are not necessarily the same.
Which format should a team use?
There is no universal winner established by the 2008 comparison. Choose based on the project’s implementation and verification flow, library data, and required analysis—not on the assumption that one format covers all power intent better in every environment.
- Confirm the project’s tool flow. Ask which format and revision the relevant synthesis, implementation, verification, and analysis tools accept and preserve. The 2008 article cannot establish present-day compatibility.
- Map required intent. List the voltage and power domains, supplies, crossings, isolation, retention controls, always-on paths, and switch behavior the design needs to express.
- Check the library boundary. Determine whether cell attributes such as level-shifter pins and retention-cell controls are represented in the power-intent file or supplied through the library flow.
- Check analysis and simulation needs. If the flow depends on power-mode-specific timing conditions, retention-control checking, corruption handling, or voltage resolution, confirm how the selected tools and format express those requirements.
- Test any conversion semantically. Because the formats organize information differently, validate that the converted intent preserves domain relationships, cell associations, control behavior, and analysis setup rather than treating successful parsing as proof of equivalence.
Allen expected in 2008 that organizations would use both formats rather than quickly converge on one. That is a period-specific forecast, not evidence about current adoption. A ResearchGate record independently identifies his article as a March 2008 comparison of the competing formats: ResearchGate publication record.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What the 2008 history does—and does not—tell you
The article describes the standards landscape as it appeared at the time: Cadence announced the Power Forward Initiative in early 2006; Cadence and the Silicon Integration Initiative created the Low Power Coalition under Si2; and the coalition released the first public CPF document in January 2007. Accellera released UPF 1.0 that same month. In January 2008, Magma, Mentor, and Synopsys announced UPF support in their tools. The article also discusses an IEEE working group for an industry-standard power-intent format as P1801.
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Those dates explain the article’s contemporary discussion of competition and possible convergence. They do not establish today’s IEEE 1801 revision, vendor support, tool behavior, or market share. The comparison remains useful for understanding why two power-intent formats can cover overlapping concepts yet differ in syntax and in where particular information lives; a present-day project decision requires checking its actual standards and tool documentation.
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