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Problems With Frequency Offset Mode - Measuring a 2X Multiplier

Question asked by superdx on Apr 17, 2015
Latest reply on Apr 26, 2015 by Dr_joel

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Hi -
I am using N5247A PNA-X, my problem is as follows:

In a Standard measurement, I perform the calibration as usual, once the calibration is done I proceed to change the frequency settings (the Cal was done for a wide-band frequency range) to apply the 2x multiplier (making sure all the frequencies ranges are correct and are covered by the performed cal). When I measure the received power into port 2 (port 1 is the source) this gives me the expected results; however, if I want to measure Gain, the measurement gives me unreasonable results. Any ideas why I can't measure gain, but I can measure the received power?

thanks :)

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daras

Apr 17, 2015 1:55 PM

Are you trying to measure the gain of the harmonic in dBc (output power at the 2X frequency / input power at X frequency) or are you trying to measure the normal gain (i.e S21)? either way, you can't do it in the same channel as the one you are using to measure the harmonic power.

if you just want to measure S21, then just copy the first channel into a new channel (this will make the new channel point to the same calibration as the original channel) and then turn off FOM and just add a S21 trace. if you had a 2-port calibration in the original channel, then your S21 will be corrected.

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ningchen

Apr 18, 2015 2:49 AM

Hi SuperDx:

I saw in another thread that your PNA-X has options of IMD measurement for converters, I'm thinking you have SMC, too. You can easily use the SMC measurement application to measure your multiplier, because the multiplier is a special version of converter. You can measure the input power at input frequency, the output power at 2X frequency and the conversion gain. With SMC you don't need two separate channels to measure the input power at 1X frequency and output power at 2X frequency with FOM.

All you need to do in SMC measurement setup is to set the numerator to 2 on the "Mixer Setup" tab, and set LO frequency to 0 on the "Mixer Frequency Tab"

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Dr_joel

Apr 26, 2015 11:57 PM

Ning Cheng is right, of course, but also we have a new application called option 089 that allows very easy measurement of harmonics, among other things.

For FOM, the receiver can only be at a single frequency, so you cannot measure the input and output in the same channel.

In 089 (which we call DIQ: Differential and IQ measurements) you can set any source to sweep any frequency and any power and any phase, and then set the receivers to measure any set of other frequencies for each source point, so you can setup a single measurement that can give you (on a doubler), the fundamental feedthrough (S21), the doubler gain (Pout @ 2x Fin/Pout @ Fin) and in fact any other product out of the doubler (such as third harmonic, etc), all in a single sweep.

Otherwise, SMC with setting LO freqeuncy to zero and RF multiplier to 2 will do the same thing but only for one product at a time.

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daras Apr 17, 2015 1:55 PM
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Are you trying to measure the gain of the harmonic in dBc (output power at the 2X frequency / input power at X frequency) or are you trying to measure the normal gain (i.e S21)? either way, you can't do it in the same channel as the one you are using to measure the harmonic power.

if you just want to measure S21, then just copy the first channel into a new channel (this will make the new channel point to the same calibration as the original channel) and then turn off FOM and just add a S21 trace. if you had a 2-port calibration in the original channel, then your S21 will be corrected.
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ningchen Apr 18, 2015 2:49 AM
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Hi SuperDx:

I saw in another thread that your PNA-X has options of IMD measurement for converters, I'm thinking you have SMC, too. You can easily use the SMC measurement application to measure your multiplier, because the multiplier is a special version of converter. You can measure the input power at input frequency, the output power at 2X frequency and the conversion gain. With SMC you don't need two separate channels to measure the input power at 1X frequency and output power at 2X frequency with FOM.

All you need to do in SMC measurement setup is to set the numerator to 2 on the "Mixer Setup" tab, and set LO frequency to 0 on the "Mixer Frequency Tab"
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Dr_joel Apr 26, 2015 11:57 PM
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Ning Cheng is right, of course, but also we have a new application called option 089 that allows very easy measurement of harmonics, among other things.

For FOM, the receiver can only be at a single frequency, so you cannot measure the input and output in the same channel.

In 089 (which we call DIQ: Differential and IQ measurements) you can set any source to sweep any frequency and any power and any phase, and then set the receivers to measure any set of other frequencies for each source point, so you can setup a single measurement that can give you (on a doubler), the fundamental feedthrough (S21), the doubler gain (Pout @ 2x Fin/Pout @ Fin) and in fact any other product out of the doubler (such as third harmonic, etc), all in a single sweep.

Otherwise, SMC with setting LO freqeuncy to zero and RF multiplier to 2 will do the same thing but only for one product at a time.
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Problems With Frequency Offset Mode - Measuring a 2X Multiplier

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