V-FET amplifier

7-10 elektor july/august 1980 0103 D6,07 MPSU03 R27 R23 36V r— T1s- I re r - -n 36V Siliconix (MOT.) R2 Op/63V R3 R130 2x 2N2222 R5 116 R26 (SW (2200) 100n N D4 7 MPSU 03 MPSU 56 VN88A F VN89AF Two years ago (Summer Circuits 1978) we published a design for an amplifier that used V-FETs in the power output stage. This design was based on an application note from Silconix. Since then we have updated the design and provided a printed circuit board for it so we felt it was worthy of inclusion here. The circuit differs from the original version in that the junction of C5/C7/R14/D9 is now connected to the output rail instead of to ground. This improves the amplifier"s per- formance considerably. Furthermore, diodes D1, D3, D6 and D7 are shown with different symbols. These are Norton diodes (constant current) as opposed to zener diodes (constant voltage). Both halves of the output stage (shown as connections Sa, Ga, Da and Sb, Gb, Db on the circuit diagram and printed circuit board) ar...