otoh, tekway tried to overcompensate (peaking) their dso to get higher bw.
actually no, the first part of frontend (up to AD8370) is not using (in my test setup) the attenuator nor compensation circuit.
The measured response is combination of :
- this part of frontend
- the 20MHz bw filter and it's influence even if off
- the LM6552 output termination
- amount of parallel connected ADCs
- parasitics
-
software When you compare to Rigol DS1000E, the first part of frontend is same, 20MHz filter similar (this is part which does have influense of the total response and partially on the bw),
LM6552 termination same, amount of ADCs diferent (which is why Rigol was not able to produce 200MHz DSO with these ADCs, this is why they used
different ADC in CA models) and software as well different (whih is for these DSOs a big difference - on Tekway i can move the -16dB point between 60MHz and 999MHz,
where of course usefull is something below nyquist frequency).
The result is flat response in compare to Rigols combination of flat and gaussian response. The "overcompensation" is typical for butterworth response, so nothing wrong here.
For gaussian DSO, such response would be however really overcompensated input.