METHOD AND DEVICE FOR THE AMPLIFICATION OF AUDIOSIGNALS IN SWITCH MODE

摘要

The method and the device are applicable in the acoustics engineering in class D amplifiers. They have reduced distortions, an extended frequency band and a dynamic range and they solve the problem of the limited time for reswitching of the end amplifying transistors. By the metod, the analogue signal is converted in analogue-digital inverter (1) to N-digit word which is divided in sub-words having Ni<N bit lengths. Each a sub-word is converted in width modulated pulse series by a respective pulse code wide pulse convertor (2 & 3) and is fed across a respective pulse transsistor amplifier (4 & 5) and demodulator (6 & 7) to a multiinput load (8) being an electroacoustic converter (loudspeaker). The analogue equivalent of each sub-word is added to those remaining in the load during the electroacoustic convertion in ratio 1 : 2 N1 : 2 N1 + N2 : 2 N1 + N2 + N3 ...., where N1, N2, N3 are the lengths of the sub-words, and N1 + N2 + N3 + ..... + N1 = N. In an electrodynamic type load, the acoustic coil contains at least two synphase windings with currents generating electromagnetic forces in the indicated ratio. In electrostatic type loads, the metallized membrane is found between the perforated electrodes at distance from them in ratio d1/d2= . In an alternative of a load of the electrostatic type the electrodes are the form of metal coating having surface ratios S1/S2= 2N1.