13
Non-Contact Oscilloscope Probes
When connected to an oscilloscope, the 3M
™
ScanEM-QC Electromagnetic
Near-Field Probe becomes a broadband non-contact probe, which is a great
diagnostics and troubleshooting tool. The typical challenge for oscilloscope
measurements is that the probe loads the circuit and affects its behavior. The
typical solution for this problem is to make 100x1 or even 1000x1 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
1000 times is too low to analyze with the scope. The ScanEM-QC Probe
makes no physical contact with the device under test, therefore it offers no
loading whatsoever on the circuit under test.
Another problem inherent with scope probes is their bandwidth. Probes
typically have 60, 100 or 250MHz 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-EQC Electromagnetic Near-Field Probe is at least 2GHz,
outperforming most any oscilloscope probe on the market. In addition, the
Typical Response of an H-Field Probe
Figure F: Typical Response of a 3M
™
Scan EM-QC Probe as an H-Field Probe
Typical response of ScanEM-HQC as a current probe
Typical response of ScanEM-EQC as a voltage probe
Typical Response of an E-Field Probe
Figure E: Typical Response of 3M
™
Scan
EM-QC Probe as an E-Field Probe
