Experimental studies of frequency response and related properties of small-signal bipolar junction transistor amplifiers

Small-signal bipolar junction transistor (BJT) amplifiers, including common -emitter (C-E), common-base, and common-collector amplifiers, ale the basic building blocks of many analog integrated circuits. An experimental invest igation of the physical analysis of the frequency response and related para meters of these amplifiers have been performed in some details. The analysi s uncovers Fundamental reasons underlying the frequency response of the amp lifiers . It indicates that although both the load resistance R-L and the c ollector resistance R-C, influence the voltage gain, for example, of a C-E amplifier, none of them should be very high to yield the highest value of t he voltage gain. The distortion of the wave form of the output signal is fo und to be a serious problem in BJT amplifier circuits. This problem is part icularly very serious in C-E amplified with square wave signal and at high frequencies. Although by-pass capacitor plays a crucial role in minimizing this problem, the contribution of the coupling capacitors in this regard ca nnot br ruled out. Physical reasons of the distortion has been discussed in some details. (C) 2001 Elsevier Science Ltd. All rights reserved.