3- laboratory work investigation of uv amplifier circuit made in bt. The purpose of the work

3- LABORATORY WORK
Investigation of UV amplifier circuit made in BT .
The purpose of the work: Experimental analysis of amplifier cascades, in which the base of the bipolar transistor (BT) in the circuits is made as a common (UB); to study the effect of the load (ohmic) resistance value on the amplifier parameters.
In the circuits, the signal source can be connected to the base YOAI emitter electrode of the BT, and the load to the collector YOAI emitter electrode. In these cases, the third electrode of the BT remains common to the input and output circuits. In the diagrams, depending on which electrode of the transistor is common to the signal (variable tOA), the transistor is said to have UE, UB, UK connections. Such circuits are called common emitter (UE), common base (UB), and common collector (UK) (Figure 3.1).
To analyze electronic circuits, it is necessary to know how the tOA and voltages between the electrodes of BT are related to each other, i.e., its volt-ampere characteristic (VAX).
In the analysis of amplifier cascades we are interested in the following parameters: power gain K _r , voltage gain coefficient K _U , the gain coefficient on tOA K _{1 , the input resistance} R _KIR and the output resistance R _{CHIQ in the} low frequency range of the amplifier cascade . At low frequencies (quasi-static mode), the gain coefficient of BT on tOA and the frequency changes of rn transitions parasitic capacitances are not taken into account. The capacitances of capacitors S1, S2 and S3 are obtained so large (mkF) that their resistance at operating frequencies cannot be taken into account. This power supply is E _K e VA applies because the S _f capacitor power supply is shunted on a variable tOA.
_Resistors R1 and R2 in Figure 3.1 are connected in parallel as resistors R _K and R _{Yu , and they are shown in the equivalent circuit in Figure 3.4 with} R11 = R1 R2 AND R KYu = R _K R _Yu .

Figure 3.1. Schematic of the amplifier stage in the UB circuit.