![]() Output Power and 1dB Compression Point (P1dB) Gain flatness refers to the variation range of amplifier gain in the entire operating frequency band under a certain temperature, and is also a main indicator of the amplifier.įigure 3. Here it is defined as the ratio of the power delivered to the load by the amplifier output port to the power actually delivered by the signal source to the amplifier input port. 2) Gain The working gain is the main indicator to measure the amplification ability of the amplifier. ![]() If the frequency starts at DC, the amplifier is considered to be a DC amplifier. At the same time, it has other important indicators, as follows: 1) Operating Frequency Generally speaking, it refers to the linear operating frequency range of the amplifier. In order to achieve high power output, the last stage must have a sufficiently high excitation power level. In the transmitting system, the output power of the RF power amplifier can be as small as mW and as large as several kW, but this refers to the output power of the final power amplifier. RF power amplifiers are electronic circuits that comprehensively consider issues such as output power, excitation level, power consumption, distortion, efficiency, size and weight. The output power and efficiency of the class C working state are the highest among these working states, and most of the amplifiers used for radio frequency work in the class C. The output of a class B amplifier is a half sine wave of the input, resulting in half-wave distortion, which produces many harmonics. Since class A amplifiers do not require additional filtering circuitry, their packages can be small and cost less. Class A power amplifier is a linear amplifier, its response to the sine-wave input is a sine-wave output, generally without distortion amplification, and the output frequency is the same as the input frequency. ![]() In the classification of amplifiers, we often talk about amplifiers of class A to E according to the conduction angle. Small signal works in class A, large signal works in class B The differences between these categories can be seen in the following table: 3) According to current conduction angle Based on it, RF power amplifiers can be divided into class A, AB, B, C, D, E and so on. The matching network of the non-resonant power amplifier is a non-resonant system, such as high-frequency transformers, transmission line transformers and other non-resonant systems, and its load properties are purely resistive, where this is also called reactance properties. 2) According to the network properties According to the nature of the matching network, power amplifiers can be divided into non-resonant power amplifiers and resonant power amplifiers. The latter does not use the frequency selection network as the load loop, but employs the transmission line with a wide frequency response as the load. The former generally uses frequency selective networks as load circuits, such as LC resonant circuits. What are the main types of RF amplifiers for such an important device? 1) According to the operating frequency bands According to the working frequency band, it can be divided into narrowband RF power amplifier and broadband RF power amplifier. Classic RF Power Amplifier Circuit Ⅱ Types of Power Amplifier in Use So you should get a full knowledge of RF power amplifiers.įigure 1. The requirements of these different aspects make the users of power amplifiers have to consider many factors in all aspects. It amplifies the modulated frequency band signal to the required power, ensuring that the receiver in the coverage area can receive a satisfactory signal level, but it cannot interfere too much with the communication of adjacent channels, and meanwhile try to keep the amplified high-power signal without distortion. The RF power amplifier is the last stage of the transmitter. To achieve stable and high-speed data transmission in various environments is one of the main goals of future mobile communication system researchers. With the vigorous development of modern digital mobile communication technology, users have more requirements on the performance of wireless communication equipment. Ⅲ Parameters of RF Power Amplifier DesignĤ.2 Influence of Nonlinear Characteristics RF Power Amplifier Design: The Basics Catalog In order to obtain a sufficiently large RF output power, a RF power amplifier must be used. In the front-end circuit of the transmitter, the power of the RF signal generated by the modulation oscillator circuit is very small, and it needs to go through a series of amplification-buffer stage, intermediate amplification stage, and final power amplification stage to obtain enough RF power before feeding. RF power amplifier is an important part of various wireless transmitters.
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