100W Basic MOSFET amplifier

Published:2013/3/13 1:04:00 Author:Ecco | Keyword: 100W , Basic MOSFET amplifier | From:SeekIC

This Basic MOSFET amplifier is very simple to build and low cost. Is perfect for Hi-Fi amplifiers and instrument amplifiers (guitar, keyboards …). Output power is + / – 100 Wrms at 8 ohm load or + / – 160 Wrms below 4 ohms. The simplicity of this circuit cause distortion + / -0.1%. Bandwidth at -3 dB is from 4 Hz to 96 Khz and it is limited by C1, R1, R2 and C2. Transistors T1 and T2 makes a first differential stage, current source of +/- 1 mA is set by R3. P1 allows a fine tuning of DC voltage at amplifier’s output. Place P1 at it’s half value for first power up, then turn it slowly for a lowest DC output voltage. It is recommended to use a first quality component. Input sensitivity is 1.2 volts. The gain of 27x is archived by R7/R6. It may be modified by changing R7 value. Transistors T5 and T6 makes the second differential stage. Transistors T3 and T4 works as a current mirror source. They push the second differential stage to drain equal current. Doing so we get a high gain and an excellent linearity. Output MOSFET transistors works in AB class, their quiescient current is set from 50 to 100 mA trough P2.



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