The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Mar 29th, 2024, 4:02am
Pages: 1
Send Topic Print
How to feed 4 RF signals with phase relationship for mixer ? (Read 5056 times)
Tiger
Junior Member
**
Offline



Posts: 10

How to feed 4 RF signals with phase relationship for mixer ?
Oct 12th, 2009, 12:15am
 
hi, all
I have met a problem when measuring a ssb-mixer:
I have to feed four signals(9GHz) with phase relationship (LOinIP,LOinIN,LOinQP, LOinQN ) for mixer(IC), and to ensure the relationship of the signals does not change when arriving at the pads of IC (the IC`s pads are connected by bondwires to PCB`s pads, and then to the SMA connectors through microstrip).
By using 90 & 180 degree Hybrids, we can generate the 4 signals from one signal source. Then, we use cables of good phase stability to transmit the four signals to the PCB`s SMA connectors.
However, we find the phase relationship of the hybrids`output are sensitive to their loads; by this I mean, if the load is exact 50om, the phase is 90 or 180 degree, while if the load is not 50om, the phase is not 90 or 180 degree either..Here comes my problem: from the SMA connector to the IC, the impedance is not exact 50 om, so the relationship of signals arriving at the IC`s pads is not what I want either..
I`d like to know your suggestions, and how you  feed 4 RF signals with phase relationship to your IC.
Many thanks!
Back to top
 
 
View Profile   IP Logged
Tiger
Junior Member
**
Offline



Posts: 10

Re: How to feed 4 RF signals with phase relationship for mixer ?
Reply #1 - Oct 13th, 2009, 1:49am
 
truely hope someone can help me
thanks!
Back to top
 
 
View Profile   IP Logged
RFICDUDE
Community Fellow
*****
Offline



Posts: 323

Re: How to feed 4 RF signals with phase relationship for mixer ?
Reply #2 - Oct 13th, 2009, 11:38am
 
Well, the not so helpful answer is that we design the phase splitter on chip using frequency dividers and symmetrical layout techniques.

On a board or hybrid I would imagine that you may need a way to tweak the phase and amplitude balance of the LO signal right at the inputs of the IC. If you do not need wideband (relative to the LO frequency) operation then you could get away with tweaking a little attenuation and capacitance for phase right at the inputs, but I suspect you need something more versatile than that for your application.
Back to top
 
 
View Profile   IP Logged
Tiger
Junior Member
**
Offline



Posts: 10

Re: How to feed 4 RF signals with phase relationship for mixer ?
Reply #3 - Oct 13th, 2009, 6:48pm
 
Many thanks, RFICDUDE
Back to top
 
 
View Profile   IP Logged
pancho_hideboo
Senior Fellow
******
Offline



Posts: 1424
Real Homeless
Re: How to feed 4 RF signals with phase relationship for mixer ?
Reply #4 - Nov 2nd, 2009, 10:59pm
 
Tiger wrote on Oct 12th, 2009, 12:15am:
However, we find the phase relationship of the hybrids`output are sensitive to their loads;
by this I mean, if the load is exact 50om, the phase is 90 or 180 degree, while if the load is not 50om, the phase is not 90 or 180 degree either..
Here comes my problem: from the SMA connector to the IC, the impedance is not exact 50 om,
so the relationship of signals arriving at the IC`s pads is not what I want either..

Try to insert attenuators(e.g. 3dB) between Hybrid's output and DUT's input.
Back to top
 
 
View Profile WWW Top+Secret Top+Secret   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2024 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.