Products > Test Equipment

Siglent SDG6000X series 200-500 MHz AWG's

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Martin72:
@Performa01:

Thank you for the cable hint, I need to make some cables for my SML01.
The two 20dB attenuators and the combiner from mini circuits I´ve ordered now from mouser (It seems that mini circuits accept only credit card, I don´t have one.), should arrive in the next week.

Performa01:

--- Quote from: gammaburst on October 05, 2023, 05:03:09 pm ---I tried your most recent test on my SDG6022X (liberated), 100.00 + 100.01 MHz using CH1+CH2 Wave Combine, both set to -30 dBm. I'm seeing about -74 dBc IMD on my old Advantest R3265M (calibrated long ago).

--- End quote ---
Well, there could be several reasons for this. Most likely you have a different HW version (mine is 01-00-00-78-38), or even a different FW (mine was 6.01.01.36R3) and finally even with identical hardware, distortion performance could vary a bit, especially since there will always be slight differences in the signal levels.

Finally, there is also the distortion of the spectrum analyzer, which can even reduce the DUT distortion measurement in some cases.


--- Quote from: gammaburst on October 05, 2023, 05:03:09 pm ---On my SDG2042X (liberated) I'm seeing about -54 dBc IMD.

--- End quote ---
Okay - looks like the SDG2000X output stage is actually less linear then. I cannot test this, since I don't have an SDG2000X.


--- Quote from: gammaburst on October 05, 2023, 05:03:09 pm ---Interestingly, if I increase its two amplitudes to -20 dBm, IMD improves to about -63 dBc. I think that's because the instrument seems to use 8 dB attenuator/relay steps, the DAC provides the smaller amplitude steps, and the amplifier distortion grows quickly with amplitude. At -30 dBm the DAC happens to be near max amplitude (higher amplifier distortion), and at -20 dBm the DAC happens to be near min amplitude (lower amplifier distortion). Just my guesses. I haven't noticed that behavior with the SDG6022X.

--- End quote ---
Yes, this most likely plays a major role, often overlooked in the heat of the fight...

mawyatt:

--- Quote from: Performa01 on October 06, 2023, 02:17:26 pm ---
--- Quote from: gammaburst on October 05, 2023, 05:03:09 pm ---I tried your most recent test on my SDG6022X (liberated), 100.00 + 100.01 MHz using CH1+CH2 Wave Combine, both set to -30 dBm. I'm seeing about -74 dBc IMD on my old Advantest R3265M (calibrated long ago).

--- End quote ---
Well, there could be several reasons for this. Most likely you have a different HW version (mine is 01-00-00-78-38), or even a different FW (mine was 6.01.01.36R3) and finally even with identical hardware, distortion performance could vary a bit, especially since there will always be slight differences in the signal levels.

Finally, there is also the distortion of the spectrum analyzer, which can even reduce the DUT distortion measurement in some cases.


--- Quote from: gammaburst on October 05, 2023, 05:03:09 pm ---On my SDG2042X (liberated) I'm seeing about -54 dBc IMD.

--- End quote ---
Okay - looks like the SDG2000X output stage is actually less linear then. I cannot test this, since I don't have an SDG2000X.


--- Quote from: gammaburst on October 05, 2023, 05:03:09 pm ---Interestingly, if I increase its two amplitudes to -20 dBm, IMD improves to about -63 dBc. I think that's because the instrument seems to use 8 dB attenuator/relay steps, the DAC provides the smaller amplitude steps, and the amplifier distortion grows quickly with amplitude. At -30 dBm the DAC happens to be near max amplitude (higher amplifier distortion), and at -20 dBm the DAC happens to be near min amplitude (lower amplifier distortion). Just my guesses. I haven't noticed that behavior with the SDG6022X.

--- End quote ---
Yes, this most likely plays a major role, often overlooked in the heat of the fight...

--- End quote ---

WRT Blue above. We get about -71dBc with our SDG6022X under same conditions, measured with SSA3021X+. SDG6022X Firmware version 36R3, and hardware version 78-38. This is OK but certainly not good enough for some serious 2 Tone IMD evaluation.


Do you have any references where this IMD reduction occurred with the use of the SA mentioned above?

Long ago we spent considerable time and $ looking into analog channels to achieve such, this was for some very specific applications. We did develop a broadband channel that exhibited a somewhat unique property, where the signal of interest odd harmonics experienced a sort of "suck out" phenomena in the classic sweep of input amplitude power and plotting the fundamental and harmonics on a power scale (dBm). The general idea was to place the input signal level utilizing AGC to place the conditioned signal within the region of the odd harmonic null, thus removing/reducing such over a wide-band without the need for tunable filters. The odd harmonic "null" looked more like a notch filter with the input power sweep.

Don't want to detract from this thread but could post something about these unique non-linear amps if folks are interested, from what I can remember from way back ???

Edit: Added the IMD plot for the SDG2042X, shows worse IMD performance as expected, just -53dBc.

Best,

Performa01:

--- Quote from: mawyatt on October 06, 2023, 03:50:11 pm ---We get about -71dBc with our SDG6022X under same conditions, measured with SSA3021X+. SDG6022X Firmware version 36R3, and hardware version 78-38.

--- End quote ---
Are you reaally sure the conditions were the same? The screenshot posted by me was named "SDG6052X_Int_1x20dB_100MHz_-6dBm" which hints on a generator output level of -6 dBm. I have not clearly described this setup, but it was the same as for the other two scenarios, with the major difference that only one input of the power combiner was connected to the SDG and the other input was just 50 ohms terminated.

To cut a long story short, the generator output was -6 dBm, and together with a total of 26 dB attenuation this resulted in a signal level of -32 dBm at the SA input.

Now I have repeated the 100 MHz test at the much lower level of -32 dBm (instead of -6 dBm) and lo and behold, my results are suspiciously close to the ones achieved by @gammaburst and you - just look at the attached screenshot.


--- Quote from: mawyatt on October 06, 2023, 03:50:11 pm ---Do you have any references where this IMD reduction occurred with the use of the SA mentioned above?

--- End quote ---
This claim is bassed on my own experience. If I find the time, I will search my old measurements to find an example eventually.

mawyatt:

--- Quote from: Performa01 on October 06, 2023, 06:56:59 pm ---
--- Quote from: mawyatt on October 06, 2023, 03:50:11 pm ---We get about -71dBc with our SDG6022X under same conditions, measured with SSA3021X+. SDG6022X Firmware version 36R3, and hardware version 78-38.

--- End quote ---
Are you reaally sure the conditions were the same? The screenshot posted by me was named "SDG6052X_Int_1x20dB_100MHz_-6dBm" which hints on a generator output level of -6 dBm. I have not clearly described this setup, but it was the same as for the other two scenarios, with the major difference that only one input of the power combiner was connected to the SDG and the other input was just 50 ohms terminated.

--- End quote ---

This was in reference to the Highlighted Blue Text which was from gamaburst as shown, so not referenced to your results with AWG set to -6dBm.

As expected your results with -30dBm AWG setting are quite similar, and agree with both gamaburst and our results, which confirms the SDG6022X performance expectations under Wave Combine.

Edit: Here's a plot with the AWG set to -6dBm with Wave Combine, we don't have a 20dB pad, so using a 10dB attenuator instead....... I know we "should" have a 20dB pad :-[

Also added (PNG36) the SDG2042X at -6dBm with 10dB attenuator, results are slightly better than when set to -30dBm as gamaburst had also shown improvement with higher levels.

Best,

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