SHC298 Datasheet, PDF (6/8 Pages) Burr-Brown (TI) – Monolithic SAMPLE/HOLD AMPLIFIER

TYPICAL PERFORMANCE CURVES (CONT)
At T_J = +25°C, ±15V supplies, 1000pF holding capacitor, –11.5V ≤ V_IN ≤ +11.5, R_L = 10kΩ, Logic Reference Voltage = 0V, and Logic Voltage = 2.5 V, unless
otherwise noted.
PHASE AND GAIN
(Input to Output, Small Signal)
CHARGE OFFSET
5
80
3.5
0
C_H = 0
70
3
C_H = 0.01µF
T_J = 25°C
–5
C_H = 1000pF
60
2.5
V_IN = 0V
C_H = 0.01µF
–10
50
2
C_H = 1000pF
40
1.5
C_H = 0.01µF
30
1
20
0.5
C_H ≥ 0.1µF
C_H = 0
10
0
1k
10k
100k
1M
10M
Frequency (Hz)
0
–0.5
0.01
0.1
1
10
100
Logic Slew Rate (V/µs)
DISCUSSION OF
SPECIFICATIONS
THROUGHPUT NONLINEARITY
Throughput nonlinearity is defined as total Hold mode,
nonadjustable, input to output error caused by charge offset,
gain nonlinearity, 1ms of droop, feedthrough, and thermal
transients. It is the inaccuracy due to these errors which
cannot be corrected by offset and gain adjustments. Through-
put nonlinearity is tested with a 1000pF holding capacitor,
10V input changes, 10µs acquisition time, and 1ms Hold
time (see Figure 1).
GAIN ACCURACY
Gain Accuracy is the difference between input and output
voltage (when in the Sample mode) due to amplifier gain
errors.
ACQUISITION TIME
Acquisition Time is the time required for the sample/hold
output to settle within a given error band of its final value
when the mode control is switched from Hold to Sample.
Control
Signal
Sample
Input
Voltage
Hold
Sample
Time
DROOP RATE
Droop Rate is the voltage decay at the output when in the
Hold mode due to storage capacitor, FET switch leakage
currents, and output amplifier bias current.
Time
FEEDTHROUGH
Feedthrough is the amount of the input voltage change that
appears at the output when the amplifier is in the Hold mode.
APERTURE TIME
Aperture Time is the time required to switch from Sample to
Hold. The time is measured from the 50% point of the mode
control transition to the time at which the output stops
tracking the input.
Output
Voltage _Gain
Error
Actual
Acquisition
Time
Ideal
Aperture Time
Offset Error
FIGURE 1. Sample/Hold Errors.
Throughput
Error
Time
®
SHC298/298A
6