Скачать или смотреть 200+ watts 8Ω or 400+ watts 4Ω Quasi-complementary QFET or HEXFET power MOSFETs output stage.

Project 52 is another CFA-based audio power amplifier project. The input stage is similar to an earlier CFA-based project, but the output stage utilizes power MOSFETs arranged in a quasi-complementary configuration. The prototype was evaluated with QFET and HEXFET power MOSFETs.

Why power MOSFETS?

Power MOSFETs have excellent performance compared to BJTs, mainly because they have positive temperature coefficient of resistance. The positive temperature coefficient of resistance means that it is essentially more stable with temperature fluctuation, protection against thermal runaway and secondary breakdown.

Another benefit of this characteristic is that MOSFETs can be operated in parallel without fear that one device will deprive current from the others. If any device begins to overheat, its resistance will increase, and its current will be directed away to cooler devices. Basically, that’s exactly what’s implemented in this project -paralleled N-channel MOSFETs.

A similar Hitachi-designed Project 5 has long been published on our website and has drawn a lot of interest from visitors.

The prototype when connected to a ±64VDC power supply rails was able to amplify a 1KHz sine wave at 1.98Vrms to 41.9Vrms across a high wattage 8Ω dummy load. This corresponds to a measured power output of 219.45 watts at 8Ω or 438.90 watts at 4Ω. The QA400 audio analyzer's test results of the prototype: THD 0.00862%, THD+N 0.01453%, SNR 79.3dB and an almost flat frequency response from 20Hz to 20KHz.

In real world listening Project 52 was very impressive and powerful, in spite of the quasi-complementary design.