Post subject: Adding two RF signals!!!
Wed Jun 01, 2005 6:03 am
Jun 01, 2005 5:57 am
I have two antiphase
Rf signals at 900MHz (not sinusoidal)...I wanna add them up. By doing
this actually I intend to cacel out the odd harmonics and add up even
Any suggestions out there !!!
have fun bye!
Wed Jun 01, 2005 11:46 am
From the description of the method
you suggest, you are not looking for a signal sumation but for some
sort of harmonic cancelation.
Because would it be a summation
the phase relationship of all harmonic would be the same.
Thu Jun 02, 2005 3:19 am
Thanks for the comments..
right..........what I want is a second harmonic, If I can.....
way is to do something like this. (with capacitors)...but this divides
the amplitude as well....
In + In-
Post subject: Adding two RF signals
Wed Jun 08, 2005 11:39 am
Unfortunately, you can't use passive
circuits to add voltages without loss.
You can only passively
add power in watts: 1Watt + 2 Watts <= 3 Watts for any kind of passive
Otherwise, adding 1V to 2v would give 3V, which gives
more power out than in: power for free - unless the signals aren't matched
impedance to begin with. And you don't get power for free.
Thu Jun 09, 2005 4:58 pm
I think you would want to actively
add the two signals. If they were at a low frequency, you would use
an op-amp, carefully adjust the input level of each signal to be the
same, and adjust the phase of one signal so the fundamental cancels
At RF, you might try to use a Gilbert cell active mixer
such as the Intersil HFA3101 or some other one with sufficient frequency
Post subject: Why not
Unread postPosted: Mon Jul 18, 2005 12:40 pm
you cannot use an op. amp. with a high bandwith? for example AD800¿1?
(I'm not sure) has 1GHz of bandwidth. Probably this a stupid question,
but I'm new in the RF.
Response to Cubeleg
Unread postPosted: Mon Jul 18, 2005 6:51 pm
When an opamp is rated at 1 GHz, the number is for the gain-bandwidth
product. An amplifier with a gain of 1 isn't particularly useful - a
1 GHz GBW opamp is really only starting to be useful as you go below