# Varactor diode

Canonical URL: https://eloragrid.ai/symbols/varactor-diode
Publisher: Elora Grid
Updated: 2026-10-14
Lookup label: VAR
Drawing use: Schematic
Reference families: Manufacturer

A reverse-biased diode whose junction capacitance is used as a voltage-controlled circuit element.

## What it represents

A reverse-biased diode whose junction capacitance is used as a voltage-controlled circuit element.
On a schematic, identify the tuning bias, cathode orientation and RF node and trace the tuned or phase-control circuit. Keep the component tag and signal/reference names consistent across the control drawing, terminal schedule and device documentation.
A varactor uses junction capacitance under reverse bias; it is not an adjustable mechanical capacitor.
Terminal letters describe electrical roles, not package pin numbers. Check the selected public datasheet for the actual pin assignment, polarity and any internally connected terminals before completing the drawing.

## How to read it

- Identify the tuning bias, cathode orientation and RF node.
- Trace the tuned or phase-control circuit.

## Information to show or reference

- Label the tuning bias, cathode orientation and RF node.
- Cross-reference the tuned or phase-control circuit.
- Add the selected device or circuit documentation revision, power/reference connections and project signal convention.

## Important distinction

A varactor uses junction capacitance under reverse bias; it is not an adjustable mechanical capacitor.

## Facts

- Common schematic mnemonic: VAR — descriptive only; project/device documentation defines reference designations.
- Terminal / interface focus: The tuning bias, cathode orientation and RF node
- Artwork scope: Original educational component glyph; not a certified standard graphic or package pinout.

## Public references

- [BB181 variable-capacitance diode documentation](https://www.nxp.com/docs/en/data-sheet/BB181.pdf) — NXP Semiconductors. Public primary manufacturer documentation establishes the component function or circuit/topology relationship. Preview geometry and drafting explanations are independently authored.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.