Master the Radio Arts
So far, everything we’ve learned about negative feedback seems to indicate that it is a great tool with little drawbacks. The only inconvenience we’ve actually talked about was a reduction in gain. Choosing a device, or a cascade of devices, that provide a big enough gain to start with solves this problem.Unfortunately, negative feedback has…
So far we’ve talked about the effects of negative feedback on gain, input resistance, and output resistance. Those are all important characteristics, but if we want to design for RF, we need to take into account one more very important characteristic: bandwidth.The most commonly used figure of merit concerning bandwidth is the 3-dB bandwidth…
When studying feedback, we are usually told that it “improves input and output resistances”, and often times we are just left with that. For us, future circuit designers, we need something much more precise. A more truthful version of the above sentence is that feedback CAN improve input and output resistances. But how and by…
We’ve learned about the basics of feedback circuits in the previous chapter. Now is the time to actually see how we can exploit feedback to our advantage. In this chapter we’re going to go through the necessary steps to exploit negative feedback in a transistor amplifier circuit. To make things more interesting and more useful…
Introduction Before diving practical amplifier circuits, we need to address the underlying theory behind feedback amplifiers. This chapter will contain the essential formulas and vocabulary to be able to move on to more practical topics. A Little Bit of Control Theory If you’ve studied automation, electronics, or mechanical engineering, chances are you’ve come across control … Read more
So far, all the designs and configurations we have explored have been open-loop amplifiers. What is an open-loop amplifier? Simply said, it is an amplifier whose action is independent of its output. No matter what the output signal looks like, the amplifier is blind to it and just amplifies its input signal. Isn’t that what…