Information

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TRANSMISSION LINE PROBES
Transmission line probes are a special type of passive probe designed for
use at very high frequencies. They replace the high impedance probe cable
found in a traditional passive probe with a precision transmission line,
with a characteristic impedance that matches the oscilloscope input
(50 Ω). This greatly reduces the input capacitance to a fraction of a
picofarad, minimizing the loading of high frequency signals. A matching
network at the tip increases the DC input resistance. While they have lower
DC input resistance than a traditional passive probe (usually 500 Ω) to
5 kΩ), the input impedance of these probes remains nearly constant over
their entire frequency range. A traditional ÷10 passive probe will have a
10 MΩ) input impedance at DC, however this impedance drops rapidly
with frequency, passing below the input impedance of a transmission line
probe at less than 100 MHz.
In some applications, transmission line probes offer advantages over
active probes. In addition to being less expensive, their passive design
is more robust to over voltage and ESD exposure. They are useful in
applications producing fast rising, narrow pulses with amplitudes which
exceed the dynamic range of active probes. They also tend to have less
parasitic effects on frequency response. A high BW transmission line
probe driving a sampling oscilloscope can be used as a “golden standard”
in situations when the response of an active probe measurement is
questioned.
Teledyne LeCroy
Transmission Line Probe
Model Numbers:
PP066
PP065
Opposite page:
PP066 Transmission Line Probe