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Figure 2.3: Schematics of an Ndigo5G board showing inter-board connectors C1 and C2.

2.2.2 Analog Inputs

TC1-1-I3M+

Lemo 00 connector

analog-offset[i]

EV10AQ190

DAC

Figure 2.4: Input circuit for each of the four analog channels.

The analog inputs of the ADC are single ended LEMO00 coax connectors. The inputs have

a 50Ω impedance and are AC coupled. The inputs are converted to a diﬀerential signal using a

balun.

Analog Oﬀsets

AC coupling removes the common mode voltage from the input signal. Users can move the

common mode voltage to a value of their choice using the analog oﬀset parameter of each

channel before sampling.

This feature is useful for highly asymmetric signals, such as pulses from TOF spectrometers

or LIDAR systems. Without analog oﬀset compensation, the pulses would begin in the middle

of the ADC range, eﬀectively cutting the dynamic range in half. By shifting the DC baseline to

one end of the ADC range, the input range can be used fully, providing the maximum dynamic

range. The analog oﬀset can be set between ±0, 25V

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