Probe Selection
TDS 620A, 640A, & 644A User Manual
amplifiers) to precisely connect your instrument to your device-under-test.
These probes have the same electrical characteristics as high speed, active
probes but use a smaller mechanical design.
Current probes enable you to directly observe and measure current wave-
forms, which can be very different from voltage signals. Tektronix current
probes are unique in that they can measure from DC to 1 GHz.
Two types of current probes are available: one that measures AC current only
and AC/DC probes that utilize the Hall effect to accurately measure the AC
and DC components of a signal. AC-only current probes use a transformer to
convert AC current flux into a voltage signal to the oscilloscope and have a
frequency response from a few hundred Hertz up to 1 GHz. AC/DC current
probes include Hall effect semiconductor devices and provide frequency
response from DC to 50 MHz.
Use a current probe by clipping its jaws around the wire carrying the current
that you want to measure. (Unlike an ammeter which you must connect in
series with the circuit.) Because current probes are non-invasive, with loading
typically in the milliohm to low range, they are especially useful where low
loading of the circuit is important. Current probes can also make differential
measurements by measuring the results of two opposing currents in two
conductors in the jaws of the probe.
Figure 3-60: A6303 Current Probe Used in the AM 503S Opt. 03
Current Probes