The Small Size Of The High Efficiency Class D Amplifier And Trancducer Matching Design

Compared with the general linear AB-class power amplifier, D-class power amplifier ismore efficient and smaller, especially suit for the environment that space limited and heattransfer condition not well. This article describes a way to design and realize D-class poweramplifier. By using a driver module with producing triangle wave, samplingsignals(comparing), MOSFET driver and various protecting circuit integrated, and carryingthe MOSFET power tube with the key parameter optimized especially for D-class poweramplifier, it can achieve high efficiency and low distortion power amplification. The size,weight and costing of the power amplifier circuit can be reduced greatly due to its small size.In addition the basic low-pass filter design method is introduced in this paper. The suitablefiter structures were separately listed for the half-bridge circuit and the bridge circuit. Simplyintroduced how to selecte the components. The PWM amplifier with no filtering is NOTcapable of amplitude modulation. It can only change times and maybe polarity. so that alow-pass filtering must designed for filtering high frequency signals and restoring lowfrequency signal. The piezoelectric ceramic transducer transforms electric signal to acousticsignals, and it can be regarded as the load of the electric signals. A good acoustic source,especially with the transducer using the best matched circuit can reduce the demand forelectric power of the power amplifier, so that to improve the efficiency of the power amplifiercircuit. The results show that, the simple matching network structure was getted through thistheory. The maximum output power and bandwith of transducer can be finded. The designprocess is relatively simple and convenient.