One still designing that it uses in the exit transistor of technology V-mosfet. This transistors to us offer a lot of virtues concerning the simple bipolar transistors, as high speeds, thermic stability, low distortion etc. Beyond this circuit use also other useful solutions as use fet as source of current [ Q3 ], trimmer TR1 with which we match the characteristics of differential amplifier of entry Q1-2. Also extensive is the use of sources of current wilson Q7-8 and Q10-11. With trimmer TR2 regulate the bias current of output stage, in the 100 ma. The use of diodes D2 until D5 in combination with the resistances R17-19, they protect the gates of transistors v-fet from exceeds the voltage ? 14V and it creates perforation in very thin layer SiO2, that is used as insulation in the gate. This way of protection is common in all the amplifiers that use these transistors. The total gain of amplifier is 32.6, regulated from the R18, R6 and R8, in the negative feedback. Also is used enough the use of local feedback for stabilisation of operation under all the conditions. Because the transistors v-fet have positive factor of temperature, with result with the increase of temperature is increased also their resistance. This increase has as result the reduction of current that via the transistor, hence also his power. The use of separated supply in the stages of drive and exit, ensures stability and reject of distortion of intermodulation. The initial drawing of is L. Hood and was published by the Wireless Word.
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