7

FN2856.6

November 19, 2004

Glossary of Terms

Acquisition Time

The time required following a “sample” command, for the output

to reach its final value within

±0.1% or ±0.01%. This is the

minimum sample time required to obtain a given accuracy, and

includes switch delay time, slewing time and settling time.

Aperture Time

The time required for the sample-and-hold switch to open,

independent of delays through the switch driver and input

amplifier circuitry. The switch opening time is that interval

between the conditions of 10% open and 90% open.

Effective Aperture Delay Time (EADT)

The difference between the digital delay time from the Hold

command to the opening of the S/H switch, and the

propagation time from the analog input to the switch.

EADT may be positive, negative or zero. If zero, the S/H

Hold command was received. For negative EADT, the output in

Hold (exclusive of pedestal and droop errors) will correspond to

Aperture Uncertainty

The range of variation in Effective Aperture Delay Time.

Aperture Uncertainty (also called Aperture Delay Uncertainty,

Aperture Time Jitter, etc.) sets a limit on the accuracy with

which a waveform can be reconstructed from sample data.

Drift Current

The net leakage current from the hold capacitor during the

hold mode. Drift current can be calculated from the droop

rate using the formula:

-IN

+IN

V-

V+

GND

CONTROL

OUT

HOLD

CAPACITOR

FIGURE 9. GUARD RING LAYOUT (BOTTOM VIEW)

I

C

∆V

∆t

--------

×

(V s

)

⁄

=

HA-2420, HA-2425