| High efficiency RF power amplifier circuit is the result of improved high-efficiency power amplifier module prominent circuit with the high output power and efficiency characteristics of the dual. In order to meet the linearity requirements and according to the baseband signal envelope of real-time adjustment of the variable bias state power devices,Communications systems meet the requirements of high efficiency power amplifier system and In many microwave and RF power amplifier circuit system, it has replaced the single amplifier transistor. Based on the instantaneous variable bias control,high power amplifier module has high efficiency, excellent linearity, low electromagnetic interference radiation and thermal radiation, etc., and the envelope detection circuit is compatible with digital bias circuit, the circuit in the specific implementation, is not difficult. So it combines the intelligent control circuit and RF power amplifier circuit and is widely used in communications equipment manufacturers widely adopted with the great future market potential of RF power amplification solution.This paper describes the classification and application of RF power amplifier and overviews research progress and trends of amplifier device. Then the detailed analysis about the basic structure of high-efficiency power amplifier, the main circuit module and the main control circuit (transfer characteristics, current and voltage detection, output power monitoring)is shared. Refer to the amplifier theory of power transistor,it builds basic amplification mechanism about the transistor and studies the relationship between linearity and efficiency for high power amplifier and provides a theoretical basis; analyzes the power monitoring circuit, current and voltage monitoring circuit and envelope monitoring part to estimate that the power amplifier meets the communications baseband signal under the premise of dynamic bias circuit design or not. It is also proposed that a multi-stage amplifier design system and RF circuit simulation tools ADS. using the ADS tool for preliminary design of the device parameters for DC simulation and small signal simulation of RF amplification; introducing of the test method about ldB compression point and third-order intercept point; exploring a way to improve the efficiency of RF power amplifier with a dynamic biasing circuit; researching the relation between harmonics and intermodulations in two aspects of amplitude and phase. Then designing the RF power amplifier with three stages with satisfying the requirements of the entire communication system, and finally drawing a multi-stage amplifier design layout and verifying all design targets with this design. |
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