Tuned Circuits in Bandpass Amplifiers

Abstract

Bandpass amplifiers can be operated both as small-signal circuits and as large-signal amplifiers, similar to the situation for lowpass amplifiers. For a small-signal amplifier, the desired overall gain (transfer) function should provide a magnitude versus frequency response such as that shown in Figure 7.1. The peak-magnitude response occurs at what is labeled the center frequency, f _o . By definition, the frequencies where the magnitude is ‘down’ from the peak value by a given amount are called the passband edges, and the interval between these is the bandwidth of the passband. Commonly, the bandedges are defined in terms of the −3dB points and the bandwidth is then called the −3dB bandwidth. These aspects are developed in greater detail in the next section.