Archive for December, 2010

plot Channel 5 is the ‘test channel’ and it appears to be noisier. Maybe due to fact that it uses a latched comparator which requires the ring oscillator to be fanned out to analog part of channel.

data files are here

looks like bandwidth is crapping out ~270MHz.  I see a definite attenuation along the input line. Perhaps the bandwidth will look better if I look at cells in block 1 rather than block 3? I will investigate…


a look at some sampled sin waves: chan2_BW_sin (you can see attenuation if you look close)

adjusted firmware timing and attempted new calibration on channel 2: ped2000_noinput_cal (RMS = 2.1 counts~1mV). here’s the output at different pedestal levels (~100mV-1V): DClevel

compare with earlier attempt to see improvement (note same scale on y-axis)

took 4000 samples at constant DC level to look at spread in readout values for one cell.  Mostly normally distributed except for some low-valued points that always seem to be present.  Sigmas presented are in units of  ‘ADC counts’ (1 count ~0.5mV)




scatter plot of data vs. readout number seems to show low values are randomly occurring:

full (all 4000 readouts) and subset of data

PSEC3 is working as expected. Here are some results:

Right now, I’m looking at one block of 64 cells in channel 2. I’ve set the pedestal at 570 mV, sampling @ 10GS/s  and operating the ADC in ~ 11bit mode. Here’s the pedestal readout over the 64 cells, sequentially triggered and readout 4 times: ped2000_cal4

where you can see fixed pattern of cell offsets: Here’s a readout of the same cells over 500 readouts: ped2000_cal500

where you can see the same pattern, more or less. I took 6000 samples and averaged each cell’s offset to remove the fixed pattern stuff. Here’s the readout before and after ‘calibration’.

Once calibrated, sampled 160MHz 100mVpp sin wave that is not resolvable without calibration.   Note: time base NOT calibrated, but each bin is roughly 100ps.

Still a lot of work to be done, but looks good so far.


The chip is alive. All channels are working. More results to come.

The chip is alive. All channels are working. More results to come.


digitized sine wave from PSEC3 (110 Mhz input @ 10 Gs/s).  need to calibrate wilkinson ADC to utilize full range, but looks like everything is working to first order.


some results (or at least an idea of what I’m trying to do)