FX-700_09 Datasheet, PDF (5/7 Pages) Vectron International, Inc – Low Jitter Frequency Translator

Tape Dimensions (mm)
A
B
C
D
16
7.5
1.5
4
Tape and Reel
Table 6. Tape and Reel Information
Reel Dimensions (mm)
E
F
G
H
I
J
8
1.5
20.2
13
50
6
K
L
16.4
178
#/Reel
500
Figure 4. Tape and Reel
FX-700 Theory of Operation
The FX-700 includes an integrated phase detector, current mode charge pump, programmable frequency dividers and VCXO. The
FX-700 will translate an input frequency such as 8 kHz, 1.544 MHz or 19.440 MHz to a specific output frequency which is an integer
multiple (1-16384) of the input frequency and less than or equal to 77.760 MHz. For clock smoothing applications, the input
frequency is typically internally divided down by a factor of 64 (2N where N = 6) by the input frequency divider and this frequency
becomes an input to the phase detector. The integrated frequency dividers (factory programmed) and crystal based VCXO allows
for a large range of possible frequency translations and clock smoothing applications.
The FX-700’s PLL is a feedback system which forces the output frequency to lock in both phase and frequency to the input
frequency. While there will be some phase error, theory states there is no frequency error. The loop filter design will dictate many
key parameters such as jitter reduction, stability, lock range and acquisition time. The external second order passive loop filter is
a complex impedance in parallel with the input capacitance of the VCXO. The loop filter converts the charge pump output into
the VCXO’s control voltage. VI’s loop filter design methodology involves the calculation of the open loop gain bandwidth and
corresponding phase margin to determine the optimal component values that ensure high loop stability and acceptable lock in
time. As a rule of thumb, the VCXO gain is typically 100 ppm/volt and the charge pump current is typically 32 uA.
VI’s Applications Engineering staff can provide the external loop filter component values required to meet specific system
requirements and application.
Suggested FX-700 Circuit Configuration Drawing
Page 5 of 7
Vectron International • 267 Lowell Road, Hudson, NH 03051 • Tel: 1-88-VECTRON-1 • http://www.vectron.com
Rev: 31Mar2009