Vertical Offset

For all passive probes, the vertical offset is controlled and limited by the oscilloscope front end hardware. The probe's attenuation affects the limits as described in Attenuation and Vertical Scale, but the offset is still controlled by the oscilloscope. The hardware offset limits are primarily determined by the current vertical scale.

Keysight has several active probes that contain their own offset summing nodes. With this, the probe is able to apply the offset before its own active amplifier. This allows the offset to be decoupled from the oscilloscope's front end and allows the probe to have a larger offset range. This lets you use a very tightly zoomed-in vertical scale and still have a large offset, letting you see tiny fluctuations in voltage on a large DC offset. When probe offset is used, it changes how the vertical offset limits are calculated. The limits are determined by the probe hardware rather than the oscilloscope hardware. This usually means that the vertical scale is no longer a factor in the offset limits. However, the limits are still multiplied by the probe's attenuation setting and any external attenuation.

While many of these offset probes allow offset only through their own summing node, some also let you select whether to use the probe's offset or the oscilloscope's offset. In general, Keysight recommends that you use the probe's offset for single-ended signals and the oscilloscope's offset for differential signals.