Copyrigh Paul Tobin, School of Electronics and Communications Engineering 1 Resonance Paul Tobin DIT

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 2 Series-tuned circuit

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 3

4 The Q-factor is a measure of SELECTIVITY.

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 5

6 The - 3dB bandwidth, resonant frequency and Q-factor

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 7 The frequency response may be used to show the relationship between Q, f o and BW

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 8 Parallel tuned circuit

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 9 Parallel tuned circuit

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 10 Equivalent parallel form

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 11 If the Q-factor is 10 or greater then Rp is the dynamic impedance of the tuned circuit

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 12 The Loaded Q-factor Any resistance, when added to a resonant circuit, will change the characteristics of that circuit Any extra resistance placed in parallel will reduce the Q-factor of the parallel tuned circuit and is hence called the loaded Q-factor. The equivalent parallel resistance of the tuned circuit Rd, is the dynamic impedance at f o.

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 13 The Loaded Q-factor R is the total loading

Copyrigh Paul Tobin, School of Electronics and Communications Engineering 14 The impedance of a tuned circuit