STB5600 Datasheet, PDF (8/10 Pages) STMicroelectronics – GPS RF FRONT-END IC

STB5600
A.3 Reference Oscillator
The recommended dual output oscillator shown in figure 6 generates both the 81.84MHz signal that is
divided down for the CPU 16.368MHz clock, but also the low amplitude 1555MHz first local oscillator
signal .
Note that some 2 volts of the 82MHz signal is available, and the capacitive tap on the tank circuit is used
to reduce the amplitude to prevent excessive radiation.
Note that the transistor must be a high frequency type, Ft of 8 GHz or greater, and that the collector
inductor must have a self resonant frequency of 2.5GHz or higher.
Fig. 6 Reference Oscillator
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