O'Reilly logo

Audio Power Amplifier Design Handbook, 4th Edition by Douglas Self

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

6

The output stage II

Distortion number 4: VAS loading distortion

Distortion 4 is that which results from the loading of the Voltage Amplifier Stage (VAS) by the non-linear input impedance of a Class-B output stage. This was looked at in Chapter 4 from the point of view of the VAS, where it was shown that since the VAS provides all the voltage gain, its collector impedance tends to be high. This renders it vulnerable to non-linear loading unless it is buffered or otherwise protected.

The VAS is routinely (though usually unknowingly) linearised by applying local negative-feedback via the dominant-pole Miller capacitor Cdom, and this is a powerful argument against any other form of compensation. If VAS distortion still adds significantly to the ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required