SA612AN DBM signals suppression question
I have an SA612AN DBM and I want to use it as a doubler, i.e feed the LO signal to both the RF in as well as the LO in.
I have two questions:
1. Which signals will be suppressed at the IF (output) as it is a DBM? The LO? The RF? Or both?
2. I guess the LO must be of higher power relative to the RF input signal. How much higher, so that to avoid the RF switching the transistors instead?
I do personally not think there will be any remarkable carrier suppression within this IC because it's has not a real "Double Balanced Configuration" because LO is driven single ended ( even other input is shorted to GND via Bias Circuit )
and it changes much its performance.Therefore there is no information about port-to-port isolation or Carrier Suppression.
If I were you, I consider differential configured Double Balanced Mixers to obtain good carrier suppression.
You mean like the minicircuits diode DBMs?
If yes, then can you please answer my first question, when using these?
BTW, MC1496 can get up to 60dB carrier suppression when NE612 can get maximum 30dB. (https://www.edaboard.com/thread62219.html) so you are quire right. I might better use the mc1496 (gain will avoid external amplifiers).
But again I want to see the answer to my first question anyway. Is the input RF also suppressed or just the LO?
Minicircuit's DBM is an option but there are also integrated solutions as Double Balanced Mixer.I don't know your operating frequency but Linear Inc. has very nice Mixers, Modulators.
In order to get a good result, RF/IF and LO should be driven as differential mode, "balanced" term is coming from there.Otherwise using balanced configuration does not make sense.
Regarding to DBM configuration and mathematics, it's clear that LO will be suppressed.
http://michaelgellis.tripod.com/gilbert.html