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Figure 2: A negative-feedback amplifier. The circuit can be explained by viewing the transistor as being under the control of negative feedback.From this viewpoint, a common-collector stage (Fig. 1) is an amplifier with full series negative feedback.
For example, in an application like this one where voltage is the output, a g-equivalent two-port could be selected for simplicity, as it uses a voltage amplifier in the output port. For R S values in the vicinity of r E the amplifier is transitional between voltage amplifier and current buffer.
In this circuit, the base terminal of the transistor serves as the input, the collector is the output, and the emitter is common to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous FET circuit is the common-source amplifier, and the analogous tube circuit is the common-cathode amplifier.
The only terminal remaining is the source. This is a common-source FET circuit. The analogous bipolar junction transistor circuit may be viewed as a transconductance amplifier or as a voltage amplifier. (See classification of amplifiers). As a transconductance amplifier, the input voltage is seen as modulating the current going to the load.
The load line diagram at right is for a resistive load in a common emitter circuit. The load line shows how the collector load resistor (R L ) constrains the circuit voltage and current. The diagram also plots the transistor's collector current I C versus collector voltage V CE for different values of base current I base .
A FET amplifier is an amplifier that uses one or more field-effect transistors (FETs). The most common type of FET amplifier is the MOSFET amplifier , which uses metal–oxide–semiconductor FETs (MOSFETs).
A radio-frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency (RF) signal into a higher-power signal. [1] Typically, RF power amplifiers are used in the final stage of a radio transmitter , their output driving the antenna .
The silicon-based RF LDMOS (radio-frequency LDMOS) is the most widely used RF power amplifier in mobile networks, [2] [3] [4] enabling the majority of the world's cellular voice and data traffic. [5] LDMOS devices are widely used in RF power amplifiers for base-stations as the requirement is for high output power with a corresponding drain to ...