Post Go back to editing

# KCC's Quizzes: AQQ229 about IP3 lab measurement

IP3 (intercept point of order 3) is a spec one find in many RF component datasheet. It is directly linked with the linearity of a function behavior.

More precisely, It indicates the amount of the intermodulation products of order 3 that interfere with the baseband.

The above pictures show the lab setup and a Spectrum Analyzer screenshot to measure the IP3 of a device (DUT) in the lab.

Questions:

1. What are the frequencies provided by sources 1 and 2?
2. What is the IP3 measured in that test?

Hide replies until user replies.
[edited by: emassa at 5:46 PM (GMT -5) on 2 Mar 2023]
Parents
• Hi Kuo-Chang,

RF is not my strong suit but I'll give it a go.

1. The frequencies are 1.25GHz and 5 MHz

2. OIP3 = Pout +deltaP/2

deltaP = -10.9 - (-45.2) or -11 - (-44.9) = 34dB ish

OIP3 = -11 + 34/2 = +6dBm

• Ah, shoot - I thought the orange thing was a mixer but it looks like it's actually a combiner, so the two frequencies will be 1.245GHz and 1.255GHz.  The third order products are at 1.235GHz and 1.265GHz.  Told you RF wasn't my strong suit...