Abstract: A driving device for a fluorescent tube has a high frequency oscillator which outputs a high frequency AC signal. A pulse width modulator is connected to the high frequency oscillator for outputting a PWM harmonic frequency signal. A first power switch is connected to the pulse width modulator for being turned off during a positive half-cycle of the PWM harmonic frequency signal and being turned on during a negative half-cycle of the PWM harmonic frequency signal. A second power switch is connected to the pulse width modulator for being turned on during the positive half-cycle of the PWM harmonic frequency signal and being turned off during the negative half-cycle of the PWM harmonic frequency signal. A piezoelectric transformer includes a primary winding having two input terminals connected to the first power switch and the second power switch, respectively, and a center terminal connected to the output terminal of the pulse width modulator.