Click here to purchase the entire book in PDF format. Maximum Output Almost every device has some maximum positive voltage (and minimum negative voltage) level which cannot be exceeded. This level is determined by a number of factors including (but not limited to) the voltage levels of the power supply rails, the operational amplifiers being used, and the gain structure of the device. The principal question in discussing the term ``maximum output'' is how we define ``maximum'' - we can say that it's the absolute maximum voltage which the device is able to output, although this is not usually the case. More often, the maximum output is defined to be the level at which some pre-determined value of distortion of the signal is incurred. If we send a sine wave into our DUT and start turning things up (either the gain of the DUT or the level of the input signal) while monitoring the output, eventually we'll reach a level where the DUT is unable to produce a high enough voltage to accurately reproduce the sine waveform (make sure that the fault lies in the DUT and not the function generator). This appears visually as a flattening of the peaks and troughs in the sine wave - called clipping because the wave is ``clipped.'' If we continue to increase the level, the flat sections will occupy more and more of the period of the signal, approaching a square wave. The more we approach the square wave, the more we are distorting the original shape of the wave. Obviously, the now-flat section of the wave is the maximum level. This is generally not the method of making this measurement. If we go back to a level just before the wave started clipping and measure the amount of distortion (we'll talk about how to do this a little later) we'll find that the distortion of the wave occurs before we can see it on an oscilloscope display. In fact, at the level at which start to see the clipping, you've already reached approximately 10$\%$ distortion. Usually, the maximum output level is the point when we have either 0.1$\%$ or 1$\%$ distortion, although this will change from manufacturer to manufacturer. Usually, when a maximum output voltage is given, the percentage of distortion will be included to tell you what the company in question means by the word ``maximum.'' Remember that the maximum output of the device is independent of its gain (because we won't know the level of the input signal). It's simply a maximum level of the output signal.