Detailed comparison of digital power amplifier
Because the digital power amplifier works completely different from the traditional analog power amplifier, it overcomes some of the inherent shortcomings of the analog power amplifier and has some unique characteristics. Overload capacity and power reserve The overload capability of the digital power amplifier circuit is much higher than the analog power amplifier. The analog power amplifier circuit is divided into Class A, B or AB power amplifier circuits. The power amplifier tube works in the linear region during normal operation. After overload, the power amplifier tube works in the saturation region, and harmonic distortion occurs. The degree of distortion increases exponentially. The sound quality deteriorates quickly. The digital power amplifier is always in the saturation region and the cutoff region when the power is amplified. As long as the power amplifier tube is not damaged, the distortion will not increase rapidly. 2. Crossover and mismatch distortion Analog Class B amplifiers have zero-crossing distortion, which is the distortion at the positive and negative crossings of the output waveform due to the non-linear characteristics of the transistor at low currents. The digital power amplifier only works in the on-off state and does not cause crossover distortion. 3. Amplifier and speaker matching Due to the large internal resistance of the power amplifier tube in the analog power amplifier, the working status of the analog power amplifier circuit will be affected by the size of the load (speaker) when matching speakers with different resistance values. The internal resistance of the digital power amplifier does not exceed 0.2惟 (the internal resistance of the switch tube plus the internal resistance of the filter), and the resistance value (4 ~ 8惟) of the load (speaker) is negligible, so there is no matching problem with the speaker. 4. Transient Intermodulation Distortion Almost all analog power amplifiers use negative feedback circuits to ensure their electro-acoustic indicators. In negative feedback circuits, in order to suppress parasitic oscillations, phase compensation circuits are used, which will cause transient intermodulation distortion. The digital power amplifier does not use any analog amplifier feedback circuit for power conversion, thereby avoiding transient intermodulation distortion. 5. Sound image localization For analog power amplifiers, there is generally a phase difference between the output signal and the input signal, and when the output power is different, the phase distortion is also different. The digital power amplifier uses digital signal amplification, so that the phase of the output signal is completely consistent with the input signal, and the phase shift is zero, so the sound image localization is accurate. 6. Upgrade Digital power amplifiers can get high power by simply replacing the switching amplifier module. The high-power switching amplifier module has lower cost and has broad development prospects in professional fields. 7. Production commissioning Analog power amplifiers have debugging problems at various working points, which is not conducive to mass production. The digital power amplifier is a digital circuit, which normally works without debugging, which is especially suitable for large-scale production.