continues to rise, XL becomes greater than XC. The impedance of the circuit increases and the current
decreases. With the circuit predominantly inductive, the current lags the applied voltage. If the output
voltage were being taken from across the resistor in Fig. 2-13, the response curve and phase angle of the
voltage would correspond to those in Fig. 2-15. As Fig. 2-15 shows, the current is highest in a region
centered on the resonant frequency. The narrow frequency range over which the current is highest is
called the bandwidth. This area is illustrated in Fig. 2-16. The upper and lower boundaries of the
bandwidth are dei ned by two cutoff frequencies designated f1 and f2 . These cutoff frequencies occur
where the current amplitude is 70.7 percent of the peak current. In the i gure, the peak circuit current is
2 mA, and the current at both the lower ( f1 ) and upper ( f2 ) cutoff frequency is 0.707 of 2 mA, or 1.414
mA. Current levels at which the response is down 70.7 percent are called the half-power points because
the power at the cutoff frequencies is one-half the power peak of the curve. P 5 I 2R 5 (0.707 Ipeak) 2R 5
0.5 Ipeak 2R The bandwidth BW of the tuned circuit is dei ned as the difference between the upper and
lower cutoff frequencies: BW 5 f2 2 f1 For example, assuming a resonant frequency of 75 kHz and upper
and lower cutoff frequencies of 76.5 and 73.5 kHz, respectively, the bandwidth is BW 5 76.5 2 73.5 5 3
kHz. The bandwidth of a resonant circuit is determined by the Q of the circuit. Recall that the Q of an
inductor is the ratio of the inductive reactance to the circuit resistance. This holds true for a series
resonant circuit, where Q is the ratio of the inductive reactance to the total circuit resistance, which
includes the resistance
continues to rise, XL becomes greater than XC. The impedance of the circuit increases and the current
decreases. With the circuit predominantly inductive, the current lags the applied voltage. If the output
voltage were being taken from across the resistor in Fig. 2-13, the response curve and phase angle of the
voltage would correspond to those in Fig. 2-15. As Fig. 2-15 shows, the current is highest in a region
centered on the resonant frequency. The narrow frequency range over which the current is highest is
called the bandwidth. This area is illustrated in Fig. 2-16. The upper and lower boundaries of the
bandwidth are dei ned by two cutoff frequencies designated f1 and f2 . These cutoff frequencies occur
where the current amplitude is 70.7 percent of the peak current. In the i gure, the peak circuit current is
2 mA, and the current at both the lower ( f1 ) and upper ( f2 ) cutoff frequency is 0.707 of 2 mA, or 1.414
mA. Current levels at which the response is down 70.7 percent are called the half-power points because
the power at the cutoff frequencies is one-half the power peak of the curve. P 5 I 2R 5 (0.707 Ipeak) 2R 5
0.5 Ipeak 2R The bandwidth BW of the tuned circuit is dei ned as the difference between the upper and
lower cutoff frequencies: BW 5 f2 2 f1 For example, assuming a resonant frequency of 75 kHz and upper
and lower cutoff frequencies of 76.5 and 73.5 kHz, respectively, the bandwidth is BW 5 76.5 2 73.5 5 3
kHz. The bandwidth of a resonant circuit is determined by the Q of the circuit. Recall that the Q of an
inductor is the ratio of the inductive reactance to the circuit resistance. This holds true for a series
resonant circuit, where Q is the ratio of the inductive reactance to the total circuit resistance, which
includes the resistance
continues to rise, XL becomes greater than XC. The impedance of the circuit increases and the current
decreases. With the circuit predominantly inductive, the current lags the applied voltage. If the output
voltage were being taken from across the resistor in Fig. 2-13, the response curve and phase angle of the
voltage would correspond to those in Fig. 2-15. As Fig. 2-15 shows, the current is highest in a region
centered on the resonant frequency. The narrow frequency range over which the current is highest is
called the bandwidth. This area is illustrated in Fig. 2-16. The upper and lower boundaries of the
bandwidth are dei ned by two cutoff frequencies designated f1 and f2 . These cutoff frequencies occur
where the current amplitude is 70.7 percent of the peak current. In the i gure, the peak circuit current is
2 mA, and the current at both the lower ( f1 ) and upper ( f2 ) cutoff frequency is 0.707 of 2 mA, or 1.414
mA. Current levels at which the response is down 70.7 percent are called the half-power points because
the power at the cutoff frequencies is one-half the power peak of the curve. P 5 I 2R 5 (0.707 Ipeak) 2R 5
0.5 Ipeak 2R The bandwidth BW of the tuned circuit is dei ned as the difference between the upper and
lower cutoff frequencies: BW 5 f2 2 f1 For example, assuming a resonant frequency of 75 kHz and upper
and lower cutoff frequencies of 76.5 and 73.5 kHz, respectively, the bandwidth is BW 5 76.5 2 73.5 5 3
kHz. The bandwidth of a resonant circuit is determined by the Q of the circuit. Recall that the Q of an
inductor is the ratio of the inductive reactance to the circuit resistance. This holds true for a series
resonant circuit, where Q is the ratio of the inductive reactance to the total circuit resistance, which
includes the resistance