SHC605 Datasheet, PDF (8/15 Pages) Burr-Brown (TI) – High-Speed Operational TRACK-AND-HOLD AMPLIFIER

TIMING DEFINITIONS
Acquisition Time is the time it takes to reacquire the input
signal when switching from the hold to track mode. This
time interval starts at 50% of the clock transition and ends
when the input signal is reacquired to within a specified
accuracy at the output. This specification does not include
the track-to-hold settling time.
Aperture Delay is a measure of the track-to-hold switch
delay time. It is the difference between the analog input
amplifier’s signal path delay and the digital track-to-hold
switch delay. A positive delay indicates the digital switch
delay is larger than the analog amplifier delay.
Aperture Jitter is random variation in the aperture delay.
This specification is measured in ps-rms and results in phase
noise on the held signal. A large aperture jitter value can
manifest itself by degrading the SNR of a sampling ADC.
Droop Rate is the change of the held output voltage as a
function of time. The measurement starts immediately after
the device switches from the track to hold mode.
Feedthrough Rejection is a measure of the amount of the
input signal that “feeds through” to the output while the
device is in the hold mode. This specification is usually a
function of frequency, with degradation at higher frequen-
cies.
Hold-to-Track Delay is the time from the track command
to the point when the output begins changing to acquire a
new signal. This delay is included in the SHC605’s specified
acquisition time.
Pedestal Offset is the error voltage step incurred at the
output when the device is switched from the track to hold
mode.
Track-to-Hold Settling Time is the time for the track to
hold transient to settle to within a specified accuracy.
+2V
Analog _0V
Input
–2V
+2V
Analog
Output ^0V
Acquisition Time
Hold to
Track
Switch
Delay
Time
–2V
“1”
Hold
Command
“0”
“Hold”
FIGURE 1. SHC605 Timing Diagram.
®
SHC605
“Track”
8
Aperture
Delay
Voltage
Level Held
Track to
Hold Settling
“Hold”