PLL
Phase-locked loop
Controls an oscillator through a phase-comparison feedback arrangement to follow the documented reference.
Schematic
Symbols · VCO
Voltage-controlled oscillator
Generates an oscillating output whose frequency responds to the documented control voltage.
Schematic · VCO
What it represents
Generates an oscillating output whose frequency responds to the documented control voltage.
On a schematic, identify the control input, supply/reference and timing components and trace the oscillator output and downstream clock or modulation circuit. Keep the component tag and signal/reference names consistent across the control drawing, terminal schedule and device documentation.
A VCO is a signal generator; the term does not mean a power-frequency generator connected to a busbar.
The preview is an independently drawn educational functional reference. Add the selected component’s actual power pins, terminal numbers, timing or analogue reference details when producing a construction drawing.
How to read it
- Identify the control input, supply/reference and timing components.
- Trace the oscillator output and downstream clock or modulation circuit.
Information to show or reference
- Label the control input, supply/reference and timing components.
- Cross-reference the oscillator output and downstream clock or modulation circuit.
- Add the selected device or circuit documentation revision, power/reference connections and project signal convention.
A distinction that matters
A VCO is a signal generator; the term does not mean a power-frequency generator connected to a busbar.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
CD4046B — phase-locked loops and voltage-controlled oscillators
Public primary manufacturer documentation establishes the component function or circuit/topology relationship. Preview geometry and drafting explanations are independently authored.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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