INFICON PLO-10i Phase Lock Oscillator - Manual (Page 60)

PLO-10 PHASE LOCK OSCILLATOR
THEORY OF OPERATION 8-12
When the above complex conductance is plotted in polar coordinates, one obtains a circle
as shown in Figure 22. The vector V indicates the magnitude and phase of the crystal
current divided by the applied voltage. The real part of the conductance is indicated by
the vector R and the imaginary part is indicated by the vector I.
Figure 22 Polar Admittance Plot of High Q Crystal
no
FREQUENCY = 4.987966 MHz
RESISTANCE = 8.6Ω
BANDWIDTH ≈ 38Hz
Q ≈130,000
OSCILLATOR
PHASE ERROR
OF 15 DEGREES
OSCILLATOR
LOCK POINT
ZERO PHASE
ERROR LOCK POINT
TRUE SERIES RESONANCE