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The Rigol DS1052E

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tinhead:
funny, the input circuit is not much different than the one from Tekway DSO:

https://www.eevblog.com/forum/index.php?topic=1571.msg21235#msg21235

The small ADC driver chip is in a LLP-8 package seems to be really LMH6552 (maybe hard to see on my picture but it is marked 88AB / 6552)

EECrAZY:
Yeah, looks like Tekway is a improved copy of Rigol with some changes on ADC/FPGA/LCD part.
Analog inputs are just routed differently and all that trigger support circuitry looks also very similar with the same parts...
I am still curious what is all that circuitry is supposed to do? Would not 1 comparator be enough? I noticed there is a LT1790 reference chip,  I thought it could be used for self calibration, but turns out like it feeds a REF pin of LTC2601 DAC. Rigol board does not have those parts.
There are a few analog multiplexers there with -1Db drop at 100Mhz, Could that be a bottleneck? Seems like the rest of the components would handle 200Mhz+ not a problem

EECrAZY:

--- Quote from: tinman on October 31, 2010, 06:28:39 pm ---that's the self-calibration unit, it runs with 125Mhz.
 
--- End quote ---
Do you mean that it has a 125Meg oscillator on board which is used for the sole purpose of selfcalibration???

tinhead:

--- Quote from: EECrAZY on October 31, 2010, 10:58:11 pm ---
--- Quote from: tinman on October 31, 2010, 06:28:39 pm ---that's the self-calibration unit, it runs with 125Mhz.
 
--- End quote ---
Do you mean that it has a 125Meg oscillator on board which is used for the sole purpose of selfcalibration???



--- End quote ---

i've answered here:
https://www.eevblog.com/forum/index.php?topic=1571.msg22123#msg22123

let's leave Rigol thread only Rigol related (even if probably Rigol is using the same self-calibration way but with different DAC)

EECrAZY:
Ok, finally took my rigol apart, warranty sticker removes very easily using the same method people use on xbox.
Measured some signals, there is a small DAC chip with "D5G" marking. Looks like its constantly fed  by CPU/FPGA, so the output is steps of different height.
DAC output feeds two 4051 multiplexors, which are being  switched by 8khz counter.
I am wondering if they use this approach to generate offset voltages, trigger levels etc with only 1 DAC?

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