The amplification process of the reflection amplifier with different positive feedback schemes is shown in Figure 2. An inductor with reactance X L and the internal nonlinear capacitance of the transistor compose the feedback circuit. The basic element of the circuit determining its principal parameters is a controlled nonlinear element (in this case a field effect transistor). The subject of this work is the study of the amplification phenomena of the amplifier working with a series positive feedback. An example of this kind of reflection amplifier has been previously reported. It contains a DC source, a nonlinear element (NE), a matched reactive load (X L), a circulator to separate the input signal (S(t)) and the output signal (P OUT), positive feedback elements (FB), and additional blocking elements (bandpass filter BF and an output capacitance C). The circuit with parallel positive feedback is the most extensively studied. ![]() 1 Basic amplification schemes for a transistor reflection amplifier. 7 In this article, as an extension of the previous work, a more detailed analysis is proposed for a reflection amplifier using mismatched resonant circuits.įig. Later on, after more research, new results were obtained. In a previous publication, 1 the authors proposed a reflection amplifier using a transistor with positive series feedback, showing a higher stability and efficiency than a reflection amplifier with parallel feedback. 2-6 One of the basic problems in the development of a reflection amplifier is its relatively narrow frequency band as well as its low stability. 1 The development of such devices has been described previously. ![]() One of the approaches to satisfy the amplification requirements at microwave frequencies is to use a reflection amplifier. In many cases, they must be amplified from a low to a higher power level by an amplifier having special basic characteristics, such as sufficient gain within a specific frequency band, low noise, stability, low power consumption and low cost. Electromagnetic signals are used to transmit information in the form of amplitude, frequency, phase and time duration of an oscillation.
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