Mixer Spur Calculator

Mixer Spur Calculator. In RF system design, a mixer produces unwanted spurious products (spurs) — signals generated at harmonic combinations of the RF and LO frequencies that can interfere with the desired output. Enter your LO Start/Stop Frequency, IF Center Frequency, IF Bandwidth, LO Side, RF Input Power, and Maximum Spur Order into the Mixer Spur Calculator to identify all in-band spurious products. Results include Total Spurious Products, Worst Spur Level, RF Frequency Range, and the Highest Order Spur present in your IF band. Also try the Smith Chart Calculator.

Mixer Spur Calculator inputs
GHz
GHz
GHz
GHz
dBm
dBm

Results

Total Spurious Products

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Worst Spur Level

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RF Frequency Range

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Highest Order Spur

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Results Table

What are mixer spurious products (spurs)?

Mixer spurs are unwanted frequency components generated when signals mix in a non-linear device. They occur at frequencies of the form M×fLO ± N×fRF, where M and N are integers, creating interference that can degrade system performance. See also our calculate Step Attenuator R1 (Series/Shunt).

How do I interpret the M×N spur analysis chart?

The M×N chart shows all possible spurious products based on harmonic mixing. M represents LO harmonics, N represents RF harmonics, and the order (|M|+|N|) indicates the spur strength - lower order spurs are typically stronger and more problematic.

What is the difference between high-side and low-side LO injection?

High-side injection means the LO frequency is higher than the RF frequency (fLO > fRF), while low-side injection means fLO < fRF. The choice affects which spurs fall within your IF passband and system image rejection requirements.

Why should I consider spurious products in mixer design?

Spurs can cause interference, desensitization, and false signals in your receiver. By analyzing spurs early in design, you can choose appropriate LO frequencies, add filtering, or adjust system architecture to minimize problematic interference.

How accurate is the spur level prediction?

Spur levels depend on mixer type, drive levels, and circuit implementation. This calculator provides theoretical estimates based on typical mixer models. Actual spur performance should be verified through measurement or detailed circuit simulation.

What spur order should I analyze?

Start with orders 2-5 for initial analysis. Higher-order spurs (6+) are typically weaker but may still be significant in sensitive applications. The calculator allows up to 10th order for comprehensive analysis.

How do I minimize spurious products in my design?

Use appropriate filtering before and after the mixer, choose LO frequencies that place spurs outside your signal band, use balanced mixers for better spur suppression, and optimize drive levels to balance conversion gain with spurious performance. You might also find our Reflection Coefficient Calculator useful.