Patent ID: 8781139

Claim:
A speaker system, comprising: a capacitive speaker; a coil speaker; and a driving circuit configured to drive the capacitive speaker and the coil speaker simultaneously, the driving circuit comprising: a D class or AB class amplifier configured to receive an audio signal and to output an amplified signal having an output voltage according to the audio signal; a first drive terminal coupled to the D class or AB class amplifier for receiving the amplified signal, the first drive terminal having a voltage conversion unit and a protection and matching unit, wherein the voltage conversion unit is configured to boost the output voltage to a first driving voltage, which is higher than the output voltage, and provide the first driving voltage and a first driving current to the capacitive speaker according to the amplified signal, and the protection and matching unit is coupled between the D class or AB class amplifier and the voltage conversion unit for impedance matching between the D class or AB class amplifier and the voltage conversion unit, the protection and matching unit configured to limit a total current flowing through the D class or AB class amplifier; and a second drive terminal connected to the first drive terminal in parallel and coupled to the D class or AB class amplifier, the second drive terminal configured to receive the amplified signal and to provide a second driving voltage and a second driving current to the coil speaker according to the amplified signal; wherein the first driving voltage is larger than the second driving voltage and the first driving current is smaller than the second driving current.