PL565-68QC-R datasheet(6/12 Pages) MICREL

6 / 12 page

(Preliminary)

Analog Frequency Multiplier

PL565-68 VCXO

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1(408) 9 44-0800 • fax +1(408) 474-1000 • www.micrel.com Rev 12/08/11 Page 6

AFM QFN PACKAGE APPLICAT ION CIRCUIT

RECOMMENDED PCB LAYOUT

 Avoid ground planes underneath the crystal

and inductor traces to limit parasitic

capacitance.

 Add bypass capacitor close to VDDBUF pin.

 Avoid bypass capacitors near VDDOSC pins to

lower cross-talk of unwanted frequencies.

 L1X(a,b) can be used to increase the VCXO

pulling range. Using a ferrite core inductor

limits the oscillation amplitude which can have

a positive effect on phase noise.

 L2X tunes the frequency multiplier tank circuit.

L2X needs to be a wire wound inductor with

high Q-factor, preferably >20.

 The large center pad is the “thermal relief” pad

and can be connected to ground.

PL565-68QC-R Datasheet(PDF) 6 Page - Micrel Semiconductor