User`s guide

3 Connecting to the Device Under Test
72 InfiniiVision Oscilloscopes User’s Guide
Analog Input Impedance (50 Ohm or 1 MOhm)
The input impedance of most InfiniiVision oscilloscope analog channels can be set to
either 50 or 1 M . (The input impedance of 6000 Series 100 MHz bandwidth models is
fixed at 1 M .) The 50  mode matches 50  cables and many active probes commonly
used in making high frequency measurements. This impedance matching gives you the
most accurate measurements because reflections are minimized along the signal path.
The 1 M impedance is commonly required for use with most passive probes.
If you would like to connect to the oscilloscope using 50 ohm BNC cables instead, select
the 50 ohm input impedance mode.
For instructions on setting the input impedance, see “Channel Coupling and Input
Impedance Selection” on page 61.
For more information on probing, visit www.agilent.com/find/scope_probes
Information about selecting a probe can be found in document number 5989-6162EN:
Agilent Oscilloscope Probes and Accessories Selection Guide, available at
www.agilent.com.
AutoProbe Interface
The AutoProbe interface uses a series of contacts directly below the channel’s BNC
connector to transfer information between the oscilloscope and the probe. When you
connect a compatible probe to the oscilloscope, the AutoProbe interface determines the
type of probe and sets the oscilloscope’s parameters (units, offset, attenuation, coupling,
and impedance) accordingly.