Model No: M760 Plus
Customer: INTEK Rev No: A
17
detector.
4. FREQUENCY STABILITY
LET : Fo = Crystal oscillator frequency
Fr = Phase detector reference frequency
Fvco = VCO frequency
Ft = Transmit frequency
Then : Fr = Fo/800
And under locked conditions : Fr = Fvco / N
WHERE, “N” is the programmable divider divide ratio.
THEN : Fvco = N X Fr
From which it can be seen, the percentage error in Ft is the same as the percentage error in Fo. The stability of the
crystal oscillator is determined primarily by the crystal itself and having lesser deviation by the active and passive
components of the oscillator. The choice of crystal and component is such that the required frequency stability is
maintained over the required voltage and temperature rang.