Category: Small Signal Amplifiers

Amplifier Testing

Amplifier Testing: Preparation – Transistor Amplifier Testing and other circuits should be tested in a methodical fashion; otherwise the results obtained may be useless. The circuit should first be carefully constructed in bread-board form, placing the components to resemble the circuit diagram as closely as possible. This makes testing and troubleshooting much easier than when […]

Capacitor Coupled Common Base Amplifier

Capacitor Coupled Common Base Amplifier: A practical Capacitor Coupled Common Base Amplifier (using a plus/minus supply) is shown in Fig. 12-39. [Note the polarity of the input coupling capacitor (C1).] The CB circuit is analysed already, where it is found to have a very low input impedance, as well as a voltage gain and output […]

Differential Amplifier Circuit using Transistors

Differential Amplifier Circuit using Transistors: The Differential Amplifier Circuit using Transistors is widely applied in integrated circuitry, because it has both good bias stability and good voltage gain without the use of large bypass capacitors. Differential amplifiers can also be constructed as discrete component circuits.   Figure 12-31(a) shows that a basic Differential Amplifier Circuit […]

BIFET Amplifier

BIFET Amplifier: BJT-FET Considerations : Two-stage BJT circuits usually have relatively low input impedances. To increase Zi, a field effect transistor may be used as the first stage. Circuits which are composed of BJTs and FETs are termed BIFET Amplifier circuits. Since a FET circuit normally has much lower voltage gain than a BJT circuit, […]

DC Feedback Pair with Two Amplification Stages

DC Feedback Pair with Two Amplification Stages: The DC Feedback Pair with Two Amplification Stages circuit shown in Fig. 12-25(a). The base of transistor Q2 is directly connected to the collector of Q1, and the base of Q1 is biased from the emitter of Q2 via resistor R2. Comparing this circuit to the capacitor-coupled circuit of Fig. […]

Two Stage Direct Coupled Common Emitter Amplifier

Two Stage Direct Coupled Common Emitter Amplifier: Figure 12-23 shows Two Stage Direct Coupled Common Emitter Amplifier. This time the second stage is a common collector circuit, or emitter follower. Stage 2 gives the circuit a very low output impedance, but has unity voltage gain Stage 1 still has substantial voltage gain.   The design […]

Direct Coupled Circuits

Direct Coupled Circuits: For economy, the number of components used in any circuit should be kept to a minimum. The use of direct coupling between stages is one way of eliminating components. Figure 12-20 shows a Direct Coupled Circuits that has the base of transistor Q2 directly coupled to the collector of Q1. Comparing this to […]

Single Stage Common Source Amplifier

Single Stage Common Source Amplifier: Bias circuit design for the Single Stage Common Source Amplifier in shown in Fig. 12-10. As with the common-emitter BJT circuit, design commences with specification of the supply voltage, amplification, frequency response, load impedance, etc. Selection of ID,RD, and Rs The circuit shown in Fig. 12-10 has no provision for […]

Capacitor Coupled Two Stage CE Amplifier

Capacitor Coupled Two Stage CE Amplifier: A Capacitor Coupled Two Stage CE Amplifier circuit is shown in Fig. 12- 15 . Stage-1 is capacitor-coupled (via C3) to the input of Stage-2. The signal is applied to the input of Stage-1, and the load is coupled to the output of Stage-2. The signal is amplified by […]

Single Stage Common Emitter Amplifier Circuit

Single Stage Common Emitter Amplifier Circuit: Specification – Bias circuit design for the Single Stage Common Emitter Amplifier Circuit in shown in Fig. 12-1 and ac analysis of the circuit is already explained. Design of this circuit (or any other circuit) normally commences with a specification which might list: the supply voltage, minimum voltage gain, […]