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User's Manual (MUT)
Mod. V1724 8 Channel 14bit - 100MS/s Digitizer
06/11/2007
7
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00103/05:V1724x.MUTx/07 V1724_REV7.DOC
63
34
Data converted by channel ADC are brought to the FPGA via a 2 bit BUS. Data transfer
timing is provided by TRG-CLK; the available bandwidth is 200 Mb/s.
The FPGA ROC handles 8 bit data. Data rate is ¼ of TRG-CLK. Chx DATA represents
the 8 MSB of the converted sample. Data from 8 channels are summed; each channel
can be enabled (see Analog Monitor Register at § 4.34) to participate or not to the sum.
The sum value is provided on 11 bit; a positive/negative offset (also encoded on 11bit)
can be added to the sum (there is a sign bit in the Analog Monitor Register AMR to select
offset polarity). The sum value can be multiplied by a fixed factor (MAGNIFY x1, x2, x4,
x8). The final result (11 bit dynamics) allows to drive the DAC. The DAC output has 1V
dynamics and drives 50 Ohm.
3.7.3.1.
Procedure to enable “Analog Monitor” mode
In order to enable Analog Monitor mode is necessary to:
−
enable the channels to send data to FPGA ROC, by setting to 1 bit 7 of Channel
Configuration register (see § 4.12). If this bit is set the datum sent is always 0.
−
Configure the Analog Monitor register with the desired settings.
−
Enable Analog Monitor mode: set to 2 the Monitor Mode register.
3.7.3.2. Applications
examples
These examples show the effect of the channel/offset/magnify parameters over MON
output.
Single channel amplified on 0-1 V dynamics:
Fig. 3.17: Example of Magnify parameter use on single channel
The assumption is an input signal on CH0 using the whole dynamics. Only such channel
is enabled for Analog Monitor; the triangular waveform is just as example. FPGA AMC of
CH0 sends 8MSB to FPGA ROC with 25 Mhz rate (one sample out of four). If no output
is added and MAGNIFY factor 1x, the DAC produces a copy of the signal on channel 0
with 0÷125 mV dynamics (1/8 of DAC dynamics). If a larger dynamics is desired, it is
necessary increase MAGNIFY factor; with MAGNIFY 8x one channel covers all the DAC
available dynamics.