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is that the probe loads the circuit and affects its behavior. The typical
solution for this problem is to make 100x1 or even 1,000x1 probes that
have extremely high input impedance and low capacitance. That may
work in some applications; but for many, the signal attenuated 100 or even
1,000 times is too low to analyze with the scope. The 3M
™
ScanEM-C
Electromagnetic Near-Field Probe makes no physical contact, therefore it
Figure E: Typical Response of 3M
™
Scan-
EM-EC Probe as a Voltage Probe
Figure F: Typical Response of 3M
™
Scan-
EM-HC Probe as a Current Probe
offers no loading whatsoever on the circuit under test.
Another problem inherent with scope probes is their bandwidth. Probes
have 60, 100 or 250 MHz bandwidth. Cost for higher-frequency probes
is prohibitively high. With today’s high-speed circuits, low-bandwidth
tools may easily miss nanosecond-long transients, leaving engineers to
wonder why their circuits behave the way they do. The bandwidth of the
3M
™
ScanEM-EC Electromagnetic Near-Field Probe is at least 2 GHz,
outperforming most any oscilloscope probe on the market. In addition, the
ScanEM-C Probe amplifies the signal instead of attenuating it, allowing the
user to view even the weakest signal on the screen.
The ScanEM-EC Probe measures an electrical field that is a representation
of the voltage in the circuit. The ScanEM-HC Probe measures a magnetic
field that is a representation of the current in the traces. You will be able to
monitor high-frequency currents on a signal or power trace without cutting
