Separating Harmonics, IMD, P1dB, and IP3 on One Graph

Question I started with

I moved beyond small-signal gain and tracked how fundamentals and distortion change as input level rises.

Separating Harmonics, IMD, P1dB, and IP3 on One Graph — concept flow — I redrew the relationships before returning to the equations.

Connecting the concepts

Second- and third-order polynomial terms create harmonics and intermodulation. P1dB is a measured compression point, while IP3 is an extrapolated intersection and not an operating point.

harmonic
IMD
P1dB
IP3
compression

Equations and assumptions

I write the reference impedance, units, and linear-versus-decibel domain before substituting numbers.

y = a1 x + a2 x^2 + a3 x^3OIP3 = P_out + Delta_IM3 / 2

Worked example

If one fundamental output is 0 dBm and adjacent IM3 is −30 dBm, ΔIM3=30 dB and OIP3≈15 dBm under the straight-line extrapolation.

Separating Harmonics, IMD, P1dB, and IP3 on One Graph — calculation relationship — This is my explanatory redraw, not an imported RFDH figure or a measurement result.

Connecting it to my coursework and projects

My coursework archive does not contain P1dB/IP3 measurement results, so this calculation is a study example rather than a new result extracted from the stored Cadence screens.

High-frequency engineering course hub

What I will check next

A high IP3 does not define all large-signal behavior; bias, bandwidth, temperature, tone spacing, memory effects, and setup also matter.

Pages I read

Official references I checked

Analog Devices: Understand Wireless Data Sheet Specifications, Part 1