Quote:
|
I would be interested to see the measurement of IIP3 and OIP3 of a ring mixer,e.g. ADE-1 or SBL-1 since you have the right equipment to do it. It will need +7dbm signal to drive the LO oscillator.
|
I've got quite a few diode ring mixers here but some caution is required when testing them. The results will depend on how well terminated the mixer ports are. Ideally a 50 ohm termination impedance is desired on all ports. If this isn't achieved then the IP3 results can be affected quite significantly.
Because of this, the results I achieve might not be replicated in a real circuit design where the ports might not have a good wideband termination on all ports.
I've got several level 7 Minicircuits mixers here including a very old SBL-1, a TUF-1 and an SRA-3. The others are level 10, level 13 and higher. The old rule of thumb for the VHF level 7 mixers was that the input 1dB compression point should be about 6dB below the LO drive level. So the input P1dB should be about +1dBm. The input IP3 should be about 15dB higher than the input 1dB compression point but this is just a crude rule of thumb.
So I'd expect to see an input IP3 of somewhere around +16dBm for these mixers. However, this will vary a bit depending on the RF, IF and LO frequencies. Also, the LO drive level will affect the result and this seems to be more critical for the higher level mixers, eg level 13.