Analog Frequency Multiplier

VCXO Family of Products

47745 Fremont Blvd., Fremont, CA 94538 TEL (510) 492-0990, FAX (510) 492-0991

www.phaselink.com

Rev.:03-22-05 Page 12

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).

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

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.

Note: Please contact PhaseLink for the Gerber

files of the board layouts.

4X Layout

2X Layout