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Power Amplifiers and Switches
Published in Nassir H. Sabah, Electronics, 2017
The emitter follower is a useful class A output stage because of its high input resistance and low output resistance, which means that most of the signal voltage appears across the load. Figure 11.2.4a shows an emitter follower biased with what is effectively a dc current source IEE. Figure 11.2.4b corresponds to Figure 11.2.2b and shows only the ac load line drawn with respect to iE and vCE axes. The quiescent point Q is located on the midpoint of the load line for maximum symmetrical swing. Neglecting the small-signal variation veb, vo follows v i. Assuming sinusoidal operation, the operating point swings between Q′ and Q″, where Vom = Vim and Iom = Vo m/RL. The load power is PL = VemIom/2. The power delivered by the supply is VCCIEE. Hence,
Discrete Transistor Circuitry
Published in Douglas Self, Small Signal Audio Design, 2020
The simple emitter-follower is lacking both in linearity and load-driving ability. The first shortcoming can be addressed by adding a second transistor to increase the negative feedback factor by increasing the open-loop-gain. This also allows the stage to be configured to give voltage gain, as the output and feedback point are no longer inherently the same. This arrangement is usually called the complementary feedback pair (hereafter CFP) though it is sometimes known as the Szilaki configuration. This circuit can be modified for constant-current or push-pull operation exactly as for the simple emitter-follower.
Equivalent Circuits for Diodes and Transistors
Published in D V Bugg, Electronics:, 2021
The emitter follower has high input impedance, low output impedance, voltage gain ≈ 1 and current gain up to (β + 1). It serves as an impedance transformer and is frequently used to drive a low impedance load such as a loudspeaker. Since the voltage gain is 1, there is no Miller effect and the high frequency performance is good.
Design reviews on a multipurpose power sockets for different applications
Published in Cogent Engineering, 2018
Chin jie Wong, Umar Nirmal, Sharmeeni Murugan
Mandalakas invented a temperature compensated solar light sensor patent no. US 3480781. In this product, two solar cells that have the same features are mounted on a thermal equalizing plate. A temperature resistor is also mounted on the plate. The cells and the resistor are able to receive the same intensity of light and same temperature as they have the same physical location and construction. The use of two solar cells can ensure that the output variations of one cell cause by temperature difference is cancelled out by another solar cell. Both solar cells are operated under short-circuit conditions for good linearity of output with intensity. The short circuit consists of an emitter follower configuration controlled by an operational amplifier (Mandalakas, 1969) . Figure 25 shows the isometric view and the circuit symbol of the solar light sensor.