
81
or dynamic resistance of a parallel tuned circuit of moderate to high
Q is given by:
R
d
=
L
CR
where
R
d
= dynamic resistance of circuit
R = resistance of components in ohms
L = inductance in henries
C = capacitance in farads
5.2 Q factor
The voltages across the inductor and capacitor in a circuit at resonance
are substantially opposite in phase (the loss resistances affect the phas-
ing slightly) and cancel each other. The voltage developed across the
inductor, usually the lossiest component, compared with the voltage
applied in series to the circuit, is a measure of the ‘goodness’ of the
circuit. This ratio is often referred to as the magnification factor, ...