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Measurements >> RF Measurements >> about mixer measurements in the real world
https://designers-guide.org/forum/YaBB.pl?num=1238217755

Message started by Tiger on Mar 27^th, 2009, 10:22pm

Title: about mixer measurements in the real world
Post by Tiger on Mar 27^th, 2009, 10:22pm

hi, all

I`m a new learner in this field, and have met some problems with mixer measurements in the real world, not eda tools:

1.for the Gilbert based mixer, the input signals are all differencial, so the mixer measurements need differencial soure generater, isn`t it?

2. for the ssb mixer which have I & Q two path, how to generate the signal having 90 degree phase? moreover, how to measure the ssb mixer NF?

many thanks for your reply

Title: Re: about mixer measurements in the real world
Post by pancho_hideboo on Mar 27^th, 2009, 11:04pm

Tiger wrote on Mar 27^th, 2009, 10:22pm:

1.for the Gilbert based mixer, the input signals are all differencial, so the mixer measurements need differencial soure generater, isn`t it?

Use 180degree Hybrid. http://www.krytar.com/html/180deg.htm
http://www.designers-guide.org/Forum/YaBB.pl?num=1233236788

Tiger wrote on Mar 27^th, 2009, 10:22pm:

2. for the ssb mixer which have I & Q two path, how to generate the signal having 90 degree phase?
moreover, how to measure the ssb mixer NF?

Use 90degree Hybrid. http://www.krytar.com/html/90deg.htm
http://innovativepp.com/90couplers.html

But I can't understand what you mean by "ssb mixer" ?

Usually "ssb mixer" means ssb upconverter, here you need to feed LOin_I, LOin_Q, BBin_I and BBin_Q for I/Q mixer.
Then you get RFout as SSB signal. In this case you need two 90degree Hybrids.
Observing point is RFout.

Or you mean complex signal downconverter by "ssb mixer", here you can get almost ssb signal if you see output signal as BBout_I+j*BBout_Q ?
In this case, you need to feed RFin(Noise Source), LOin_I and LOin_Q for I/Q mixer. You need one 90degree Hybrid.
Observing point is BBout_I or BBout_Q.

You can also get SSB signal by another scheme.
Here you need to feed RFin_I, RFin_Q, LOin for I/Q mixer. You need one 90degree Hybrid. Then you can get almost ssb signal if you see output signal as BBout_I+j*BBout_Q You need one 90degree Hybrid.
Observing point is BBout_I or BBout_Q.

http://www.designers-guide.org/Forum/YaBB.pl?num=1164118091
http://www.designers-guide.org/Forum/YaBB.pl?num=1221172918

Title: Re: about mixer measurements in the real world
Post by Tiger on Apr 3^rd, 2009, 12:23am

thanks a lot pancho hideboo