Analog Frequency Multiplier
PL560-xx VCXO Family
ꢀ
theꢀamplitudeꢀonꢀtheꢀscopeꢀisꢀmaximumꢀandꢀrecordꢀtheꢀgeneratorꢀfrequency.ꢀꢀForꢀexample,ꢀtheꢀpeakꢀisꢀrecordedꢀ
atꢀ29.8x2ꢀorꢀ59.6ꢀMHz.ꢀ
ꢀ
Measuring 320 MHz L2X: ConnectꢀtheꢀRFꢀgeneratorꢀandꢀscopeꢀprobeꢀasꢀshownꢀinꢀFigureꢀ6,ꢀabove.ꢀꢀꢀWhileꢀ
powerꢀisꢀappliedꢀtoꢀtheꢀPCB,ꢀsetꢀtheꢀgeneratorꢀoutputꢀtoꢀ+12ꢀdBmꢀandꢀtheꢀfrequencyꢀtoꢀ80ꢀMHz.ꢀꢀSinceꢀthisꢀisꢀtheꢀ
2xꢀportꢀtheꢀscopeꢀwillꢀshowꢀ160ꢀMHzꢀwithꢀ~ꢀ3Vꢀpkꢁpkꢀamplitude.ꢀꢀVaryꢀtheꢀgeneratorꢀaboveꢀandꢀbelowꢀ80ꢀMHzꢀ
untilꢀtheꢀamplitudeꢀonꢀtheꢀscopeꢀisꢀmaximumꢀandꢀrecordꢀtheꢀgeneratorꢀfrequency.ꢀꢀForꢀexample,ꢀtheꢀpeakꢀisꢀ
recordedꢀatꢀ78.0ꢀxꢀ2ꢀ=ꢀ156ꢀMHzꢀ
ꢀ
InꢀtheꢀAFMꢀTuningꢀAssistant,ꢀaddꢀtheꢀscope’sꢀprobeꢀcapacitanceꢀtoꢀtheꢀCstrayꢀcell.ꢀꢀForꢀourꢀexampleꢀ0.5ꢀpFꢀ+ꢀ1.0ꢀ
pFꢀ=ꢀ1.5ꢀpF.ꢀWithꢀL2Xꢀatꢀ24ꢀnHꢀadjustꢀLWB1ꢀ(cellꢀB23)ꢀuntilꢀtheꢀpeakꢀfrequencyꢀreadsꢀ156ꢀMHz.ꢀꢀNextꢀreplaceꢀtheꢀ
L2Xꢀvalueꢀwithꢀ180ꢀnHꢀandꢀseeꢀifꢀitꢀpeaksꢀatꢀ59.6ꢀMHz.ꢀꢀIfꢀitꢀdoesꢀnot,ꢀadjustꢀCstrayꢀuntilꢀ59.4ꢀMHzꢀisꢀachieved.ꢀꢀ
Againꢀenterꢀ24ꢀnHꢀforꢀL2XꢀandꢀfineꢀtuneꢀLWB1ꢀforꢀ156ꢀMHz.ꢀ
Results: LWB1 = 1.6 nH, Cstray = 2.9 pF-0.5 pF = 2.4 pF (subtract scope probe stray capacitance)
RepeatꢀtheꢀsameꢀstepsꢀforꢀtheꢀL4X:ꢀSetꢀtheꢀgeneratorꢀtoꢀ80ꢀMHz.ꢀꢀTheꢀ82ꢀnHꢀpeaksꢀatꢀ118ꢀMHzꢀandꢀtheꢀ10ꢀnHꢀ
peaksꢀatꢀ304ꢀMHz.ꢀ
Results: LWB1 = 1.8 nH, Cstray = 2.5 pF-0.5 pF = 2.0 pF (subtract scope probe stray capacitance)
Internal Capacitor Selection by Device
Cinternal (pF)
Device Number
2X
4X
P560ꢁ0xꢀ
P560ꢁ3xꢀ
P560ꢁ4xꢀ
P560ꢁ6xꢀ
7.625ꢀ
34.125ꢀ
34.125ꢀ
7.625ꢀ
6.250ꢀ
16.500ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
47745ꢀFremontꢀBlvd.,ꢀFremont,ꢀCAꢀ94538ꢀꢀTELꢀ(510)ꢀ492ꢁ0990,ꢀFAXꢀ(510)ꢀ492ꢁ0991ꢀꢀꢀ www.phaselink.comꢀꢀꢀꢀꢀRev.:02ꢁ09ꢁ07ꢀꢀPageꢀ8ꢀꢀ
PLL [ PHASELINK CORPORATION ]
