| 摘要 |
A method and device for driving a digital speaker based on code conversion are provided in the invention. The method comprises the steps of: (1) converting input format; (2) performing multi-bit Σ-Δ modulation; (3) thermometer code conversion; (4) dynamic mismatch-shaping processing; (5) pulse width modulation code conversion; and (6) controlling on/off status switching of the MOSFET of a full-bridge power amplification network to drive a digital speaker load sound. The device comprises a sound source, an input format converter, a multi-bit Σ-Δ modulator, a thermometer coder, a dynamic mismatch shaper, a code converter, a multi-channel digital amplifier and a digital speaker load which are connected to each other in sequence. By means of the device and method of the invention, the switching rate of the power tube, the power dissipation and heating generated during the switching are reduced, the sound quality and efficiency of electroacoustic restoration are improved, the volume, weight and implementation cost of the system are decreased, and the level of electromagnetic radiation is reduced. Furthermore, the device and method of the invention also have excellent immunity to the frequency response deviation of multiple digital channels. |
| 主权项 |
1. A method for driving a digital speaker based on code conversion, successively comprises steps of:
(1) converting input signals into pulse code modulated (PCM) signals meeting a requirement of expected parameters; (2) performing multi-bit Σ-Δ modulation to the PCM signals, to push the noise energy within an audio bandwidth out of the audio band; (3) converting low-bit PCM signals having a bit-width of M bit into 1-bit coded signals corresponding to 2M transmission channels of a digital power amplifier and a speaker load by a thermometer code conversion, and distributing the coded signals to 2M digital channels in terms of equal weight, the digital signals of each channel only having two coding states of ‘0’ and ‘1’; (4) applying dynamic mismatch-shaping to the binary status code vectors of 2M channels obtained by the thermometer code conversion based on the binary status codes of ‘0’ and ‘1’, to eliminate harmonic distortion components arisen from a frequency response difference between post-stage digital-to-analog conversion loads of 2M channels and reduce the noise amplitude; (5) converting pulse density modulation (PDM) coded signals of each channel obtained after multi-bit Σ-Δ modulation and dynamic mismatch-shaping into pulse width modulation (PWM) coded signals; and (6) controlling the on/off status switching of the MOSFET of a full-bridge power amplification network to drive a digital speaker load sound, in such a way that each digital transmission channel controls the on/off action of the full-bridge power amplification circuit by differential PWM signals formed by the converted PWM coded signals and the inverse signals thereof. |
