VCO (Voltage Controlled Oscillator) Calculator

A Voltage Controlled Oscillator (VCO) is a circuit that produces an output frequency determined by an input voltage — used in synthesizers, PLLs, signal generators, and communication systems. Enter your Control Voltage, Reference Voltage, Timing Capacitor, Timing Resistor, VCO Gain (Kv), and VCO Type into the VCO Calculator to find the Output Frequency. Secondary outputs include frequency in kHz and MHz, oscillation Period, and Frequency Deviation from the reference point. Also try the find PFD Frequency with PLL PFD Frequency Calculator.

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Output Frequency

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Frequency (kHz)

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Frequency (MHz)

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Period

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Frequency Deviation

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Results Table

Frequently Asked Questions

What is a voltage controlled oscillator (VCO)?

A VCO is an electronic oscillator whose frequency is controlled by an input voltage. It converts a control voltage into a corresponding frequency output, making it essential in PLLs, frequency synthesizers, and modulation circuits. See also our use the 555 Timer PWM Calculator.

How does control voltage affect VCO frequency?

The relationship depends on the VCO type. Linear VCOs have a direct proportional relationship, while exponential VCOs have a logarithmic response. Higher control voltages typically produce higher output frequencies.

What components determine VCO frequency range?

The timing capacitor and resistor primarily determine the frequency range. Smaller capacitance and resistance values increase the operating frequency, while larger values decrease it.

What is VCO gain (Kv) and why is it important?

VCO gain (Kv) represents the frequency change per unit voltage change, measured in Hz/V. It determines the sensitivity of the oscillator and is crucial for PLL stability and modulation depth calculations. You might also find our 555 Timer Monostable Calculator useful.

How do I choose between linear and exponential VCO types?

Linear VCOs provide constant gain across the control voltage range, ideal for frequency modulation. Exponential VCOs offer wider frequency ranges and are commonly used in synthesizers and musical applications.

What frequency ranges are typical for different VCO applications?

Audio VCOs operate from Hz to kHz, RF VCOs from MHz to GHz. Low frequency VCOs (sub-MHz) are used in control systems, while high frequency VCOs serve in communication and radar systems.

How does temperature affect VCO performance?

Temperature changes affect component values, causing frequency drift. High-quality VCOs use temperature compensation techniques and stable components to minimize drift, typically specified as ppm/°C.

What is the difference between narrow band and wide band VCOs?

Narrow band VCOs have limited frequency deviation (typically <10%) optimized for stability and low phase noise. Wide band VCOs cover broader frequency ranges but may have higher phase noise and reduced stability.