Copyright © 2020
Alazar Technologies Inc.
ATS9353 User Manual
45
Analog Input
The two analog input channels are referenced to common ground in bipolar
mode. These settings are fixed; therefore, neither the reference nor the polarity
of input channels can be changed. You cannot use CH A or CH B to make
differential measurements or measure floating signals unless you subtract the
digital waveforms in software.
For accurate measurements, make sure the signal being measured is referenced
to the same ground as your ATS9353 by attaching the cable’s ground shield to
the signal ground.
The External Trigger input (labeled TRIG IN) either has a fixed input range of
±3 V with 50
Ω
input impedance, or can be configured as a TTL input with
6.3
kΩ ±10% input impedance
.
The CH A and CH B inputs have fixed DC coupling, a fixed 50
Ω
input
impedance, and a ±400 mV fixed input range.
The fixed input range is one of the main differentiators between ATS9353 and
ATS9352. Due to this fixed input range, ATS9353 provides a > 6 dB
improvement in SNR (signal-to-noise-ratio).
The ATS9353 has an additional low-frequency analog input (labeled AN IN) that
is capable of sampling at 200 KS/s. The acquired value of the third analog input
is embedded into a Footer that is appended at the end of each record, so that
software can easily correlate all three analog input channels. The main
application for this low-frequency analog input is in OCT systems where tracking
or feedback signals need to be monitored in real time.
The
low-frequency corner
in an AC-coupled circuit is the frequency below which
signals are attenuated by at least 3 dB. The low-frequency corner is
approximately 100 kHz with 50
Ω
input impedance.