Just to define the term for everyone, Equivalent Time Sampling is when you take advantage of the fact that a waveform repeats, so by sampling 10 different cycles of the same waveform at 50kHz with slightly different offsets on the ADC timing, you can recover a signal sampled at 500kHz. This only works if every cycle of the signal is identical, though.

The way I understand EST, and correct me if I'm wrong, is that you have lower-rate ADCs sampling at a 360/n degree offsets. So you might have a 100 kHz clock driving two 50 kHz ADCs at offsets, giving every second clock pulse to each respective ADC. In other words, you

*are* sampling from the same waveform.

But unless they've overclocked the ADCs (or come up with a way to disprove the Nyquist-Shannon theorem :p ) that won't get them anywhere near the claimed 250 kHz bandwidth. Actually, looking closer at the datasheet, what is claimed is that the

**full power** signal bandwidth of the ADC is 50 kHz, which I guess means there's a roll-off above that frequency? The conversion time of the ADC is 5 µs, giving an effective sample rate of 200 kHz if run at the maximum speed, or for two running in parallel, 400 kHz, giving a crusty 200 kHz effective Nyquist bandwidth. Not quite 250 kHz, but we're starting to get into the plausible territory.