Pulse-frequency modulation
represents an analog signal using only two levels
Pulse-frequency modulation (PFM) is a modulation method for representing an analog signal using only two levels (1 and 0). It is analogous to pulse-width modulation (PWM), in which the magnitude of an analog signal is encoded in the duty cycle of a square wave. Unlike PWM, in which the width of square pulses is varied at a constant frequency, PFM fixes the width of square pulses while varying the frequency. In other words, the frequency of the pulse train is varied in accordance with the instantaneous amplitude of the modulating signal at sampling intervals. The amplitude and width of the pulses are kept constant.
Applications
PFM is a method of encoding analog signals into trains of square pulses and therefore has a wide variety of applications. There are practical difficulties in the design of electronics when working with non-fixed frequencies, such as transmission line effects in board layout and magnetic component selection, so generally, PWM mode is preferred. There are, however, select cases in which PFM mode is advantageous.
Buck converters
PFM mode is a common technique for increasing the efficiency of switching step-down DC-DC converters (buck converters) when driving light loads.
In medium to high loads, the DC resistance of buck converter switching elements tends to dominate the overall efficiency of the buck converter.
This brief starts where responsible research should: with the source description of “Pulse-frequency modulation” as represents an analog signal using only two levels. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the general reference register because the source frames it as represents an analog signal using only two levels. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Sep 28, 2025. The linked authority identifier is Q2066418. None of the 0 selected statements returned an explicit reference.
A concise general-reference account can conceal disagreements about scope, terminology or the weight assigned to individual sources. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Pulse-frequency modulation”, its source revision and the description used here.
- Expand the search: follow Pulse-frequency modulation primary sources, Pulse-frequency modulation archive and Pulse-frequency research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Pulse-frequency modulation”?
- Which cited source is closest to the event, object or claim?
- What terminology or title could unlock a more precise catalogue search?
Search terms from this dossier
This entry incorporates text from “Pulse-frequency modulation” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.