Analog Frequency Multiplier
VCXO Family of Products
Measuring 320 MHz L2x:
Connect the RF generator and scope probe as shown in Figure 6, above. While
power is applied to the PCB, set the generator output to +12 dBm and the frequency to 80 MHz. Since this is the
2x port the scope will show 160 MHz with ~ 3v pk-pk amplitude. Vary the generator above and below 80 MHz
until the amplitude on the scope is maximum and record the generator frequency. For example peak accorded at
78.0 x 2 = 156 MHz
In the AFM Tuning Assistant, add the scope’s probe capacitance to the Cstray cell. For our example 0.5 pF + 1.0
pF = 1.5 pF. With L2X at 24 nH adjust LWB1 (cell B23) until the peak frequency reads 156 MHz. Next replace the
L2x value with 180 nH and see if it peaks at 59.6 MHz. IF it it does not, adjust the Cstray until 59.4 MHz is
achieved. Again enter 24 nH for L2x and fine tune LWB1 for 156 MHz.
Results: LWB1 = 1.6 nH, Cstray = 2.9 pF-0.5 pF = 2.4 pF (subtract scope probe stray)
Repeat the same steps for the L4X: Set the generator to 80 MHz. The 82 nH peaks at 118 MHz and the 10 nH
peaks at 304 MHz.
Results: LWB1 = 1.8 nH, Cstray = 2.5 pF-0.5 pF = 2.0 pF (subtract scope probe stray)
Internal Capacitor Selection by Device
Device Number
2X
P560-0X
P560-3X
P560-4X
P560-6X
7.625
34.125
34.125
7.625
Cinternal (pF)
4X
6.250
16.500
47745 Fremont Blvd., Fremont, CA 94538 TEL (510) 492-0990, FAX (510) 492-0991
www.phaselink.com
Rev.:03-22-05 Page 8
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