Analog Frequency Multiplier
VCXO Family of Products
BOARD LAYOUT DESIGN CONSIDERATIONS FOR AFMs
L2x and L4x: Try to reduce the PCB trace
inductance to a minimum by placing L2x and L4x as
physically close to their respective pins as possible.
Also be sure to bypass each Vdd connection
especially taking care to place a 0.01 uF bypass at
the Vdd side of L2x and L4x (See recommended
layout).
Note: Please contact PhaseLink for the Gerber
files of the board layouts.
Crystal connections: Be sure to keep the ground
plane under the crystal connections continuous so
that the stray capacitace is consistent on both
crystal connections. Also be sure to keep the crystal
connections symmetrical with respect to one another
and the crystal connection pins of the IC. If you
chose to use a series capacitance and or inductor to
fine tune the crystal frequency be sure to put
symmetrical pads for this cap on both crystal pins
(see Cadj in recommended layout). Even if one of
the capacitors with be a 0.01 uf and the other is
used to tune the frequency. And to further maintain
a symmetrical balance on a crystal that may have
more internal Cstray on one pin or the other. Place
capacitor pads (Cbal) on each crystal lead to ground
(see recommended layout). You can refer to (xxx) if
tuning of Cbal is required. R3rd is only required if a
3rd overtone crystal is used.
4X Layout
Vdd and Gnd: Bypass VDDANA and VDDBUF with
separate bypass capacitors and if a Vdd plane is
used feel each bypass cap with its own via. And be
sure to connect any ground pin including the bypass
caps with short via connection to the ground plane.
OESEL: J1 is recommended so the same PCB
layout can be used for both Output Enable low (No
J1) or Output Enable high (J1 = ohms) if this
function is chosen.
2X Layout
47745 Fremont Blvd., Fremont, CA 94538 TEL (510) 492-0990, FAX (510) 492-0991 www.phaselink.com Rev.:03-22-05 Page 12
PLL [ PHASELINK CORPORATION ]
