INFICON RQCM - Quartz Crystal Microbalance Research System - Manual (Page 69)

RQCM – RESEARCH QUARTZ CRYSTAL MICROBALANCE
THEORY OF OPERATION 5-17
5.7.3 FREQUENCY ERROR DUE TO IMPERFECT CAPACITANCE CANCELLATION
The effect of imperfect electrode capacitance cancellation can also be viewed as an equivalent
phase error. This error is directly proportional to crystal resistance. The equivalent phase error
due to a non-zero shunt capacitance equal to 1 pfd is one degree for a crystal with a series
resistance of 556 Ω. Since the equivalent phase error is proportional to the crystal resistance, a 1-
pfd residual capacitance error will result in a 10-degree equivalent error for a sensing crystal with
a resistance of 5.56 KΩ.
Figure 25 Equivalent Phase Error Due to Imperfect Capacitance Cancellation
Polar Plot of Crystal Conductance