Tektronix P7313SMA, Техническое описание

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Operating Basics
In the case where single-ended measurements are made on signals with a large common-mode DC voltage, it should be
noted that the use of the 50
Ω termination topology effectively attenuates the DC common-mode voltage by half. If this is
taken into account as an offset to the displayed signal, it allows single-ended signals with a relatively large DC common-mode
voltage to be measured.
If only the AC component of the single-ended signal needs to be measured, then the open input topology provides
the greatest dynamic range.
Although it is possible to attenuate an input signal with external attenuators to increase the effective dynamic range, care
should be taken to account for the signal loading and the impact on the termination voltage of the probe.
If an external attenuator is used, its attenuation accuracy must be taken into account when factoring the impact on
measurement accuracy. The increase in attenuation also brings an increase in noise.
Extending the Input Connections
At times it may be necessary to extend the probe inputs with cables that are longer than the standard 38 inch cables. The
38 inch cables are precision-matched to minimize time-delay differences (skew).
If you substitute cables, you should use low-loss, fl exible cables and keep the lengths matched and as short as possible
to minimize skew and optimize common-mode rejection. Check the skew between the cables, and if necessary, use a
pair of phase adjusters to minimize the skew.
Extending the input leads will also increase the skin loss and dielectric loss, which may result in distorted high-frequency
pulse edges. You must take into account any effects caused by the extended leads when you take a measurement.
P7313SMA Technical Reference 17