How to measure OIP3 point of mixer ?

Hello Sir

how to measure OIP3 point of mixer practically and theoretically ?
please give me practical setup also.
VNA , signal gerator and spectrum analyzer are available to me , how to use it to measure SNR ?

Thank You

Basically, you want to apply two tones into the RF input, spaced 1-5MHz apart. Call these F1 and F2. Then depending on what your LO is, you measure measure the output power levels of the F2 +/- Flo product (P1) and the 2*F2 - F1 +/- Flo product (P3 third order distortion power). The +/- is if you're mixing up or down. Now if you increase your input tones by 1dB, the third order tones will go up 3dB. The output third order intercept (OIP3) is where these are of equal power. OIP3 = 3/2 * P1 - 1/2 * P3

This may be done with a VNA, provided it can do the frequency offset measurement mentioned the appnote that vfone attached, but you may still be short on sig generators. Also, it's preferable that the two input powers are equal, but it's not critical. The equation changes a bit if they're unbalanced. The RFCafe page below has more info on that.

RF Cafe - Cascaded Budget 2-Tone, 3rd-Order Compression Point IP3