An ideal transistor would show 0% distortion in amplifying a signal. Its gain would extend to all frequencies. It would control hundreds of amperes of current, at hundreds of degrees C. In practice, available devices show distortion. Amplification is limited…

Like all electrical and electronic components, transistors are limited in the amount of voltage and current each one can handle without sustaining damage. Since transistors are more complex than some of the other components you’re used to seeing at this…

Bipolar Junction Transistor or BJT Current Mirror An often-used circuit applying the bipolar junction transistor is the so-called current mirror, which serves as a simple current regulator, supplying nearly constant current to a load over a wide range of load…

Input impedance varies considerably with the circuit configuration shown in Figure below. It also varies with biasing. Not considered here, the input impedance is complex and varies with frequency. For the common-emitter and common-collector, it is base resistance times β.…

If some percentage of an amplifier’s output signal is connected to the input, so that the amplifier amplifies part of its output signal, we have what is known as feedback. Feedback Categories Feedback comes in two varieties: positive (also called…

To overcome the challenge of creating necessary DC bias voltage for an amplifier’s input signal without resorting to the insertion of a battery in series with the AC signal source, we used a voltage divider connected across the DC power…

Although transistor switching circuits operate without bias, it is unusual for analog circuits to operate without bias. One of the few examples is “TR One, one transistor radio” TR One, Ch 9 with an amplified AM (amplitude modulation) detector. Note…

In the common-emitter section of this chapter, we saw a SPICE analysis where the output waveform resembled a half-wave rectified shape: only half of the input waveform was reproduced, with the other half being completely cut off. Since our purpose…

While the C-B (common-base) amplifier is known for wider bandwidth than the C-E (common-emitter) configuration, the low input impedance (10s of Ω) of C-B is a limitation for many applications. The solution is to precede the C-B stage by a…

The final transistor amplifier configuration (Figure below) we need to study is the common-base amplifiers. This configuration is more complex than the other two and is less common due to its strange operating characteristics. Common-base amplifier Why is it Called…

Our next transistor configuration to study is a bit simpler for gain calculations. Called the common-collector configuration, its schematic diagram is shown in the figure below. Common collector amplifier has collector common to both input and output. It is called…

At the beginning of this chapter, it illustrates how transistors could be used as switches, operating in either their “saturation” or “cutoff” modes. In the last section, we saw how transistors behave within their “active” modes, between the far limits…

When a transistor is in the fully-off state (like an open switch), it is said to be cutoff. Conversely, when it is fully conductive between emitter and collector (passing as much current through the collector as the collector power supply…