Low Capacitance Probes

Low capacitance probes (also called Z0 probes or controlled impedance probes) are passive probes that have very low input capacitance. These probes are a useful choice for some applications. While Tektronix offers the fastest handheld low capacitance probe with the lowest input C, users need to be aware of the potential pitfalls. In situations where the in-circuit source impedance is not known to be low, as compared to the impedance of a controlled impedance probe, an active probe solution with sufficiently high DC input resistance should be used in these situations.

Low impedance probes have been found to load the LVDS lines too heavily. With certain technologies such as LVDS it has been found that low capacitance probes load the signal and change the duty cycle. This loading generally shows up in the measurement as reduced amplitude, modified timing and other errors in the measurement. While the P6150 and P6158 provide low capacitive loading measurements for a variety of today's technologies, generally a high impedance probe is suggested for use with high-speed LVDS signals.

Low Capacitance Probes (50 Ω Divider Probes)

Low capacitance passive voltage probe offerings provide wide bandpass, but at the cost of resistive loading. (Some circuitry can drive the loading introduced by a low capacitance probe, but some not.)

Characteristics

*1 Limited by scope input or 42 V_RMS.