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November 2016
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ing of current changes to switching activities,
e. g. when transmitting radio sequences or
entering power save mode. The large dynamic
range and high sensitivity of its analog input
channels make this oscilloscope suited for
measuring low voltages and currents. A sensi-
tive current probe can measure currents down
to 1mA at 120 MHz bandwidth. In HD mode
dynamic variations as small as 100 µA can be
resolved. Using an analog channel to perform
current measurements provides a fixed time
reference to the other measurement signals.
Figure 4 shows an example of a current probe
in channel 3 (orange) measuring a current of
1.7mA during a sleep sequence. The current
consumption is correlated with the radio sig-
nal output on channel 1 (yellow) and the sys-
tem activity at the UART interface. During the
sleep sequence, the module does not transmit
any radio signals, but it receives regular pag-
ing signals from the base station. The current
consumption briefly increases to 105mA and
the module transmits a UART-coded commu-
nications signal on the clear-to-send (CTS)
line, which is acquired with a digital channel.
The powerful FFT-based spectrum analysis
function on all analog input channels opens
up additional possibilities, e.g. analyzing
radio signals, EMI debugging to find inter-
ferers in the spectrum or spectral analysis of
power supplies. In contrast to conventional
Figure 2. Example of a multi-domain application – IoT module with Wi-Fi radio module,
battery-operated power supply and USB interface
Figure 3. Multi-domain application in a state-of-the-art embedded design: analog measurements
in the time domain, measurements in the spectrum as well as protocol and logic analysis
