Operational amplifiers circuit configurations

Fig.4. Data plot for a 20 nA current pulse. The pulse width was 16.5 fis. The circuit used for this data consisted of a single transistor in a common emitter configuration with a light emitting diode as the load element. This circuit was used instead of the operational amplifier circuit in Fig.l because it provides improved response at low current levels.

Table 11.4 —Various configurations for operational amplifier circuits (a) inverting amplifier, (b) summing inverting amplifier, (c) current follower, (d) differential amplifier, (e) integrator, (f) differentiator.

Some circuit configurations with operational amplifiers. 

Recall that in the noninverting configuration, the operational amplifier works to keep F and Rj equal and that the cell current is supplied by the operational amplifier to maintain this condition. If wc consider the path between the inverting input and the circuit comniim at the output, we see that... 

Amplifier class of operation An alphabetical tag associated with an amplifier configuration describing its bias condition (which, in turn, determines its conduction angle) and sometimes its external circuit configuration. 

The BJT is a three electrode or triode electron device. When connected in a circuit it is usually operated as a two-port, or two-terminal, pair device as shown in Fig. 7.8. Therefore, one of the three electrodes of the BJT must be common to both the input and output ports. Thus, there are three basic BJT configurations, common emitter (CE), common base (CB), and common collector (CC), as shown in Fig. 7.8. The most often used configuration, especially for amplifiers, is the common-emitter (CE), although the other two configurations are used in some apphcations. 

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