Understanding Third Order Intercept

This video introduces third order intercept (TOI), also known as IP3, the industry-standard metric for quantifying RF device linearity. When devices operate in their non-linear region, they generate harmonics and intermodulation products. The critical third order products are particularly problematic because they fall close to the fundamental signals and are difficult to filter out. You’ll learn that third order products grow 3 dB for every 1 dB increase in fundamental power, making TOI an essential specification for amplifiers, mixers, and receivers. The tutorial covers the two-tone test methodology, source isolation techniques, and how to use attenuation to verify measurements.

What you’ll learn:

• The relationship between linearity, harmonics, and intermodulation distortion (IMD) and why third order products are especially problematic due to their proximity to fundamental signals
• How third order intercept (TOI/IP3) quantifies device linearity using a two-tone test methodology
• Proper measurement techniques including source isolation and attenuation verification to ensure IMD originates from the device under test rather than the test equipment

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