Karakterizacija linearnega močnostnega ojačevalnika razreda AB

Čajdo, Maid (author), Lavrič, Henrik (mentor)

Diplomsko delo obravnava karakterizacijo linearnega močnostnega avdio ojačevalnika razreda AB, zasnovanega po vezju The Leach Amp. V teoretičnem delu so predstavljeni osnovni principi delovanja analognih avdio ojačevalnikov, razredi delovanja ter zgradba in princip delovanja obravnavanega ojačevalnika. Poseben poudarek diplomskega dela je namenjen eksperimentalni karakterizaciji ojačevalnika in analizi njegovih zmogljivosti. V praktičnem delu je bil ojačevalnik sestavljen ter podvržen obsežnim laboratorijskim meritvam. Karakterizacija je obsegala merjenje napetostnega ojačenja, frekvenčnega odziva, izhodne moči, izkoristka, razmerja signal–šum (SNR), skupnega harmonskega popačenja (THD), intermodulacijskega popačenja (IMD), presluha in podobno. Izvedena je bila tudi primerjava delovanja ojačevalnika pri uporabi klasičnega linearnega in stikalnega napajalnika. Rezultati meritev so pokazali, da ojačevalnik dosega pričakovane karakteristike za linearni močnostni avdio ojačevalnik razreda AB ter zagotavlja dobro kakovost reprodukcije avdio signala. Izmerjeni frekvenčni odziv je širok in v območju avdio frekvenc dovolj linearen, medtem ko so izmerjene vrednosti šuma, popačenja in podobnih karakteristik potrdile pričakovano delovanje ojačevalnika. Pri meritvah je bil zaznan tudi vpliv omrežnega šuma, ki je v manjši meri vplival na nekatere merjene parametre, predvsem na skupno raven šuma in vrednost SNR. Rezultati so prav tako pokazali vpliv vrste napajalnika na delovanje ojačevalnika, pri čemer je klasični linearni napajalnik dosegel boljše rezultate glede popačenja v primerjavi s stikalnim napajalnikom. Rezultati meritev energijskega izkoristka so nekoliko presegli pričakovanja, saj so bile izmerjene vrednosti zelo blizu teoretičnemu maksimumu. Izmerjene karakteristike omogočajo celovito oceno delovanja ojačevalnika ter kažejo vpliv posameznih parametrov na njegovo zmogljivost in kakovost reprodukcije avdio signala. Na koncu je predstavljena tudi tabela, v kateri so zbrane nekatere osnovne izmerjene karakteristike in specifikacije obravnavanega ojačevalnika.

• Language: Slovenian
• Keywords: ojačevalnik, AB-razred, The Leach Amp, karakterizacija, laboratorijske meritve, SNR, THD, TIM, IMD, presluh, frekvenčni odziv.
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FE - Faculty of Electrical Engineering
• Year: 2026
• PID: 20.500.12556/RUL-187363
• COBISS.SI-ID: 293713155
• Publication date in RUL: 10.09.2026

Secondary language

• Language: English
• Title: Characterisation of an AB-Class linear power amplifier

Abstract

Diploma thesis deals with the characterization of a linear class AB power audio amplifier based on The Leach Amp circuit. The theoretical part presents the basic operating principles of analog audio amplifiers, amplifier classes, as well as the structure and operating principle of the amplifier under study. The main focus is on the experimental characterization of the amplifier and the analysis of its performance. In the practical part, the amplifier was assembled and subjected to extensive laboratory measurements. The characterisation included measurements of voltage gain, frequency response, output power, efficiency, signal-to-noise ratio (SNR), total harmonic distortion (THD), intermodulation distortion (IMD), crosstalk, and other parameters. A comparison of the amplifier's performance using a conventional linear power supply and a switching power supply was also carried out. The measurement results showed that the amplifier achieves the expected characteristics for a linear class AB power audio amplifier and provides good audio signal reproduction quality. The measured frequency response is wide and sufficiently linear within the audio frequency range, while the measured noise, distortion, and other characteristics confirmed the expected performance of the amplifier. The influence of mains noise was also detected during the measurements, which to a minor extent affected some of the measured parameters, particularly the overall noise level and SNR. The results also demonstrated the influence of the power supply type on the amplifier's performance, with the conventional linear power supply achieving better distortion performance compared to the switching power supply. The measured efficiency results slightly exceeded expectations, as the measured values were very close to the theoretical maximum. The measured characteristics provide a comprehensive assessment of the amplifier's performance and demonstrate the influence of individual parameters on its performance and audio signal reproduction quality. Finally, a table is provided summarising some of the basic measured characteristics and specifications of the amplifier under study.

• Keywords: power amplifier, class AB, The Leach Amp, characterisation, laboratory measurements, SNR, THD, TIM, IMD, crosstalk, frequency response.