RF ComponentsReceiver Architecture

Mixer Operation & Frequency Conversion

A mixer is the heart of every radio receiver — it shifts signals from one frequency to another, like translating between languages.

Mixer Multiplication & Spectrum — Live Animation
The RF input and local oscillator (LO) are multiplied together. The resulting product contains both the difference frequency (IF) and the sum frequency, as predicted by the trigonometric product formula.
RF inputLOProduct×=Frequency →Power2IF 3LO5RF8Sum
Core Concepts

Quick Reference
Key mixer relationships and formulas
Mixing product formulacos(A)·cos(B) = ½[cos(A−B)+cos(A+B)]
IF frequencyf_IF = f_RF − f_LO
Image frequencyf_im = f_LO − f_IF
Spur orderOrder = |m| + |n| for m·fRF ± n·fLO
IIP3 estimateIIP3 ≈ P1dB + 10 dB
Passive mixer lossTypically 6–8 dB conversion loss
Related Tools
Put these concepts to work

Mixer Spur Chart

Visualise all mixing products for any RF/LO combination and identify problematic spurs

IMD Calculator

Calculate intermodulation distortion products and IP3 for your receiver chain