Penguat Audio Kelas D Dengan Umpan Balik Tipe Butterworth

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Gunawan Dewantoro
Franciscus Dalu Setiaji
Tio Pragustha

Keywords

Abstract

A class D amplifier would, in ideal sense, amplify signals without any noises and distortions which yield 100% efficiency and 0% Total Harmonic Distortion (THD). However, class D amplifiers have some drawbacks that lead to nonlinearity and increasing THD. Therefore, a feedback mechanism was employed to enhance THD performance of amplifier. Some feedback techniques have been using first order filter in the feedback path to retrieve audio signals. This research proposed a second order filter with Butterworth approach. A power amplifier was realized using full-bridge amplifier with MOSFETs to provide greater power. This class D amplifier was designed to meet following specifications: maximum output power up to 32.6 W with an 8 Ω load, sensitivity of 90 mV/W, frequency response ranging from 20 Hz – 20 kHz with tolerance ± 1 dB, THD as low as 1.1 %, SNR up to 90.16 dB, and efficiency of 82.1%.   

Keywords : Class D Amplifier, Feedback, Butterworth, Total Harmonic Distortion
                                                                                  

Abstrak—Proses penguatan sinyal pada penguat kelas D idealnya tidak terdapat derau dan distorsi sehingga penguat kelas D dapat menghasilkan efisiensi hingga 100 % dan THD (Total Harmonic Distortion) 0%. Namun pada praktisnya, penguat kelas D memiliki beberapa kekurangan yang menyebabkan keluaran penguat kelas D menjadi tidak linear sehingga mengakibatkan naiknya THD. Oleh karena permasalahan tersebut, diberikan sutau mekanisme umpan balik negatif yang dapat memperbaiki kualitas THD dari penguat. Beberapa teknik umpan balik negatif menggunakan tapis orde 1 pada umpan balik untuk mendapatkan frekuensi audio. Penelitian ini merancang teknik umpan balik negatif menggunakan tapis orde 2 dengan pendekatan Butterworth. Penguat daya diwujudkan menggunakan penguat jembatan penuh dengan MOSFET yang dapat menghasilkan daya lebih besar. Penguat kelas D yang dibuat mempunyai spesifikasi antara lain: daya keluaran maksimum mencapai 32,6 Watt pada beban 8 Ω, dengan kepekaan penguat 90 mV/W, memiliki tanggapan frekuensi 20 Hz – 20 kHz dengan toleransi ± 1 dB, THD dengan umpan balik mencapai 1,1 % , SNR hingga 90,16 dB serta efisiensi penguat mencapai 82,1%.                                                      

Kata Kunci : Penguat Kelas D, Umpan Balik, Butterworth, Total Harmonic Distortion


References

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