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Need a good model for multi-signal input mixer simulation

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goldensol

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when multi-signal input mixer.
I want to get the power of the intermodulation signal.
The HB method can't get the right answer.
could you give me a good model to simulation it.
 

flatulent

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mixer simulator

The Watkins-Johnson co. application notes say to add all of the input signal powers and take half. Use this number in the usual IP3 equation to get the average IMD levels. This works very well for a large number of input signals such as appear at the input of a radio receiver.
 

VSWR

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simulation mixer

What model are you using for the mixer? A double balanced mixer modeled with four Schottky diodes and two transformers? Which analysis program are you using?

It's important you get reasonable conversion loss of the mixer in the analysis program, prior to applying multi tone input signal. If you model a low level double balanced mixer, the conversion loss shall be around 6-7 dB for +10 dBm of LO drive power level. The 1 dB compression point shall be about 0 dBm or so. As long as you don't get approx these figures it's meaningless starting applying multi tone input carriers.

GaAs FET

goldensol said:
when multi-signal input mixer.
I want to get the power of the intermodulation signal.
The HB method can't get the right answer.
could you give me a good model to simulation it.
 

toonafishy

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programa simula um mixer

When you say it is wrong, are the frequencies missing, wrong or the wrong level?
Harmonic balance should work just fine. Be sure to tell it where to look for the solution frequencies. HB is not smart enough to find the output frequencies itself. As a very minimum, you should specify the RFin, LO and the sum and difference output products (ie the upper and lower sideband frequencies). Also tell it you want to look out at least to the third harmonic of each frequency.
 

goldensol

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mixer simulations

flatulent said:
The Watkins-Johnson co. application notes say to add all of the input signal powers and take half. Use this number in the usual IP3 equation to get the average IMD levels. This works very well for a large number of input signals such as appear at the input of a radio receiver.
could you give me the link to get the application
 

flatulent

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mixer input ip3 calculation

Here is a link to all notes.

http://www.wj.com/technotes/index.asp

It is in one of the ones on mixers. It would be worth your while to download all of them and read them during your spare time.

The information I gave you is from memory 15 years ago. You will have to nose around each mixer note for the details.
 

goldensol

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simulator mixer

For example,two tone(f1,f2) input the mixer.the frequency have the relation:
f1+IF=f2
f2+IF=Lo
I want to get each of the level of these frequency:
f2-f1;
3*f2-2*f1-Lo;
LO-f2;
2*Lo-3*f1+f1;
.........
 

dainis

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double balanced mixer simulation model

Look Agilent free AppCad:
h**p://w*w.semiconductor.agilent.com/spg/doc/wirelessDesignTools/AppCad/setupex.exe
 

Needbias

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watkins johnson receiver

I think any commercial Harmonic-balance simulator can solve this problem easily.Just try.Microwave office is a good software.
 

flatulent

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software simulation mixer

I have been nosing around and found the following:

The Voltera series is used for these analysis types. (Use a simulator that has this method)

A book, Solid-State Microwave Amplifier Design by Ha 1981 has chapter 6 on this subject.

In general, the amplitude of the term formed by mixing several signals will be proportional to the product of the amplitudes of each of the signals raised to the power that is equal to the frequency multiplication.

For instance, the spectral line formed by M times signal 1 minus N times signal 2 will have an amplitude proportional to the amplitude of signal 1 raised to the M power times the amplitude of signal 2 raised to the N power. This product is further multiplied by the H term with the subscript (M plus N) of the Voltera series.

To make use of this without a voltera simulator, you can do a few simulations of two signals and back out to get the H terms.
 

goldensol

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mixer simulation

THanks flatulent
I will try what you say
 

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