AD809
REV. A
–4–
DEFINITION OF TERMS
Maximum, Minimum and Typical Specifications
Specifications for every parameter are derived from statistical
analyses of data taken on multiple devices from multiple wafer
lots. Typical specifications are the mean of the distribution of
the data for that parameter. If a parameter has a maximum (or a
minimum), that value is calculated by adding to (or subtracting
from) the mean six times the standard deviation of the distribu-
tion. This procedure is intended to tolerate production varia-
tions: if the mean shifts by 1.5 standard deviations, the remaining
4.5 standard deviations still provide a failure rate of only 3.4
parts per million. For all tested parameters, the test limits are
guardbanded to account for tester variation to thus guarantee
that no device is shipped outside of data sheet
specifications.
Capture and Tracking Range
This is the range of input data rates over which the AD809 will
remain in lock.
Jitter
This is the dynamic displacement of digital signal edges from
their long term average positions, measured in degrees rms.
Jitter on the input clock causes jitter on the synthesized clock.
Output Jitter
This is the jitter on the synthesized clock (OUTPUT, OUTPUT),
in degrees rms.
Jitter Transfer
The AD809 exhibits a low-pass filter response to jitter applied
to its input data.
Bandwidth
This describes the frequency at which the AD809 attenuates
sinusoidal input jitter by 3 dB.
Peaking
This describes the maximum jitter gain of the AD809 in dB.
Damping Factor, z
Damping factor, ζ describes the compensation of the second or-
der PLL. A larger value of ζ corresponds to more damping and
less peaking in the jitter transfer function.
Duty Cycle Tolerance
The AD809 exhibits a duty cycle tolerance that is measured
by applying an input signal (nominal input frequency) with a
known duty cycle imbalance and measuring the ×8 or ×16
output frequency.
Symmetry-Recovered Clock Duty Cycle
Symmetry is calculated as (100× on time)/period, where on time
equals the time that the clock signal is greater than the midpoint
between its “0” level and its “1” level.
Typical Characteristic Curves
POPULATION – Devices
RMS JITTER – Degrees
1200
1000
0
More1. 8
800
600
400
200
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4
100
90
80
70
60
50
40
30
20
10
0
CUMULATIVE – %
AD809 FREQUENCY SYNTHESIZER
JITTER DISTRIBUTION MATRIX
75 DEVICES (3 LOTS)
[ECL, TTL] × [×8, ×16] × [RISE, FALL] × [+4.5V, +5.0V, +5.5V] × [–40°C, +25°C, +85°C]
THIS CHART DESCRIBES THE
AD809 OUTPUT JITTER
SPECIFICATION OVER MANY
CONDITIONS. THE DATA
REPRESENTED ARE TAKEN
WITH RESPECT TO THE RISING
AND FALLING EDGES, FOR
EACH FREQUENCY RANGE,
LOCKED TO EITHER TTL OR
ECL INPUT, OVER ALL
TEMPERATURE AND SUPPLY
CONDITIONS.
0.0
FREQUENCY
CUMULATIVE %
Figure 2. Jitter Histogram
INPUT DUTY CYCLE – %
RMS JITTER – Degrees
1.9
1.3
1.0
0 10010 20 30 40 50 60 70 80 90
1.8
1.2
1.1
1.6
1.4
1.7
1.5
T
A
= +25°C
V
CC
= +5V
19.44MHz
9 72MHz
Figure 3. Jitter vs. Input Duty Cycle
