Window detector

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window detector circuit diagram

A window detector circuit, also called window comparator circuit or dual edge limit detector circuits is used to determine whether an unknown input is between two precise reference threshold voltages.[1] It employs two comparators to detect over-voltage or under-voltage.[2]

Each single comparator detects the common input voltage against one of two reference voltages, normally upper and lower limits.[3] Outputs behind a logic gate like AND detect the input as in range of the so-called "window" between upper and lower reference.

Window detectors are used in industrial alarms, level sensor and controls, digital computers and production-line testing.[citation needed]


Truth table
Uin A B Y
> Urefbot 0 1 0
< Ureftop 1 0 0
< Ureftop
> Urefbot
1 1 1

If Uin is greater than Urefbot and Uin is lower than Ureftop then both comparators' outputs will swing to the logical high and turn on the AND gate output.

See also[edit]


  1. ^ Ramón Pallás-Areny; John G. Webster (1999). Analog Signal Processing. John Wiley & Sons. pp. 287–. ISBN 978-0-471-12528-0.
  2. ^ Bali (2008). Linear Integrated Circuits. Tata McGraw-Hill Education. pp. 155–. ISBN 978-0-07-064807-4.
  3. ^ Steve Ciarcia (1990). Ciarcia's Circuit Cellar. Circuit Cellar. pp. 1–. ISBN 978-0-07-010969-8.

Further reading[edit]