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TDS 684A, TDS 744A, & TDS 784A Service Manual
1–21
Typical Characteristics
This subsection contains tables that list the various typical characteristics which
describe the TDS 684A and 7XXA Digitizing Oscilloscopes.
Typical characteristics are described in terms of typical or average performance.
Typical characteristics are not warranted.
Table 1–15: Typical Characteristics — Signal Acquisition System
Name Description
Accuracy, Delta Time Measurement The limits are given in the following table for signals having amplitude greater than
5 divisions, reference level = 50%, filter set to (sinX/X), acquired at 5 mV/div or greater.
For the TDS 7XXA, pulse duration < 10 div. Channel skew not included.
For the Single Shot condition, 1.4 ≤ T
r
/S
i
≤ 4, where S
i
is the sample interval and T
r
is
the displayed rise time.
TDS 684A: For the averaged condition, 1.4 ≤ T
r
/W
i
≤ 40, where W
i
is the Waveform
Interval, as described elsewhere in these specifications.
TDS 684A: Extra error in the measurement will occur for two-channel measurements due
to channel-to-channel skew. This is described elsewhere in these specifications.
Conditions Time Measurement Accuracy
Single Shot or Sample
mode (or HiRes mode
on the TDS 7XXA),
Full Bandwidth se-
lected
TDS 684A:±( (0.20 × sample interval) + (100 ppm × | Reading |)
+ (0.05 × W
i
) )
TDS 684A example: at 5 GS/s, 5 ns/div, measuring a 40 ns wide
pulse, accuracy = ±( 40 ps + 4 ps + 5 ps) = ±49 ps.
TDS 7XXA: ±≥ 0.15 sample interval + 25 ppm × | Reading | +
t/div/1000
TDS 7XXA example: at 4 Gs/s, accuracy = 37.5 ps
≥ 100 Averages, Full
Bandwidth selected.
TDS 7XXA: repetitive
TDS 684A: ±( 10 ps + (100 ppm × | Reading |) + (0.25 × W
i
) )
TDS 7XXA: 20 ps + (25 ppm × | Reading |) + t/div/1000
Calculated Rise Time
1
Volts/Div Setting 684A Rise Time
744A
Rise
Time
784A Rise Time
10 mV/div – 1 V/div
5 mV/div – 9.95 mV/
div
2 mV/div – 4.98 mV/
div
1 mV/div – 1.99 mV/
div
450 ps
600 ps
750 ps
900 ps
800 ps
800 ps
800 ps
890 ns
400 ps
530 ps
600 ns
800 ns