PL565-68 Datasheet, PDF (6/12 Pages) Micrel Semiconductor – Analog Frequency Multiplier

(Preliminary) Analog Frequency Multiplier
PL565-68 VCXO
AFM QFN PACKAGE APPLICATION 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.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax [phone] • www.micrel.com Rev 12/08/11 Page 6