I finally got some spare time to measure the level accuracy and amplitude flatness of the SDG6052X as a sine signal source for e.g. frequency response measurements.
As a comparison (and as a sanity check for my measurements) I’m including the corresponding results for a high performance signal generator (Anritsu MG3633A), which features excellent phase noise, high output power and good amplitude accuracy, especially if it is operated below 500MHz.
The Siglent SDG6052X can replace an RF signal generator in many situations, if the following limitations are observed:
• Maximum output level is limited to 0dBm for the full frequency range of 500MHz (Anritsu MG3633A: +19dBm up to >1GHz)
• Output levels below -56dBm require external attenuators (Anritsu MG3633A: internal attenuator to -140dBm)
So the first test is for the maximum output level of 0dBm:
SDG6052X Level Accuracy 0dBm
As we can see, the output level is a little on the low side on my unit with an average error of -0.1dB. There are weird discontinuities of +0.12dB at 1MHz and -0.12dB at 300 and 400MHz, but the overall amplitude flatness is rather decent at +0.08/-0.17dB (0.25dB peak to peak deviation).
Compare this to the Anritsu MG633A:
MG3633A Level Accuracy 0dBm
The Output level is spot-on with an average error of just -0.01dB. There are no discontinuities and the amplitude flatness is excellent at +0.09/-0.11dB (0.2dB peak to peak deviation).
When comparing the two devices, we should keep in mind that the Anritsu MG3633A is a 2.7GHz generator, so it can easily give excellent performance in the small subrange of 500MHz, whereas the Siglent SDG 6052X has to approach its absolute bandwidth limits.
Yet there is a sweet spot for the SDG6052X when it is operated at -30dBm:
SDG6052X Level Accuracy -30dBm
Once again the output level is a little low with an average error of -0.05dB. The only discontinuity of +0.1dB occurs at 1MHz again and the amplitude flatness is sensational at +0.06/-0.04dB (0.1dB peak to peak deviation).
In the same situation, the Anritsu MG3633A performs slightly worse:
MG3633A Level Accuracy -30dBm
Output level is a little high with an average error of +0.11dB. There are no discontinuities and the amplitude flatness is excellent at +0.07/-0.1dB (0.17dB peak to peak deviation).
I’ve tested all output levels from 0dBm down to -50dBm (in 10dB steps), but below -40dBm (100nW) my power meter introduces additional errors. At least all meaurements are very consistent with the results from the MG3633A.
The measurement results are only shown for frequencies above 100kHz because the power sensor is specified for 200kHz to 18GHz. It works well enough down to at least 20kHz, but the additional errors cannot be ignored anymore when we’re expecting accuracies of better than 0.1 decibel.
Here is a table overview of my measurements:
SDG6052X Level Accuracy Table
Level is the nominal signal level as it was set on the generator.
Min. is the minimum absolute level over the full measurement bandwidth.
Max. is the maximum absolute level over the full measurement bandwidth.
Err_max is the maximum absolute amplitude error over the full measurement bandwidth.
Mean is the average absolute amplitude level.
Dev+ is the positive peak deviation of the output level relative to
Mean.
Dev- is the negative peak deviation of the output level relative to
Mean.
Here is an overview of the SDG6052X measurements, starting at 10kHz (
which is outside the specification of the power sensor!):
SDG6052X Level Accuracy Overview
EDIT: Frequency response overview graph added.