Study And Design Of Broadband Power Amplifier

In recent decades,the rapid development of wireless communication technology has not only promoted the military field to modernization,but also greatly improved people's living standards.It can be said that wireless communication technology has become an indispensable tool in our work and life.Besides,the signal transceiver is a key component of a communication system,where the power amplifier acts as an important module in the transmitter link.The function of the power amplifier is to amplify the weak signal generated by the pre-stage to obtain a sufficiently high power and then radiated to the antenna for long distance radiation.Therefore,the performance of the power amplifier directly affects the overall quality of the transmitter,which is critical.In addition,wireless communication has been widely used in many fields and various types of communication systems have been derived.These systems have different modes of operation,different communication standards,and different modulation methods,which in turn raises a problem:Multiple communication systems are independent of each other and cannot be interconnected.When coordination and cooperation are required,multiple systems need to be integrated on the same platform,so that the cost is increased and the reliability is also significantly reduced.To solve this problem,the concept of a broadband communication system has been proposed,and the research on broadband power amplifiers has developed.The so-called broadband power amplifier,as its name suggests,is to achieve sufficient bandwidth in addition to the power,efficiency and other performances required for narrow-band power amplifier design,which requires special consideration of its in-band gain flatness performance.In addition,broadband power amplifiers generally require more complex matching networks and design of bias circuits,which results in relatively large chip sizes.Therefore,how to expand the bandwidth of the amplifier and make the layout area more compact with other performances meeting the requirements becomes a difficult problem for designers.In order to achieve large bandwidth,the author innovatively proposes a combination of lossy matching,negative feedback as well as the Forward Combining structure based on several tipical topologies that are widely used at present.In addition,this design achieves the goal of reducing area by using the simplest inter-level matching structure and the flexibility of matching with capacitors and microstrip lines.Finally,after reasonable optimization of circuit parameters and proper design of the circuit layout,good comprehensive performance was obtained.The main work of the two designs is as follows:(1)Based on the 0.25?m GaAs pHEMT process,a wide-band power amplifier covering the entire X-band is designed by rationally utilizing the lossy matching structure and the negative feedback structure.The post-imitation results show that the power amplifier has a saturated output power of 30 dBm in the operating frequency range of 7 to 14 GHz,the corresponding power added efficiency is over 31%,the power gain is greater than 20 dB,and the gain flatness is±0.45 dB.Moreover,by adopting the form of the simplest inter-level matching,the layout achieves a very small area occupation of only 1.52 mm~2.(2)Based on the 0.25?m GaAs pHEMT process,a wideband power amplifier covering the entire X-band is designed using Forward Combining technology.The post-imitation results show that compared with the design(1),in the same operating frequency band,the power amplifier achieves a 30 dBm saturated output power while the power gain is significantly increased due to the elimination of the loss caused by the consumable components.24.6 dB with a power added efficiency of over 33%.However,the gain flatness deteriorates to some extent by±1 dB.In addition,the rational use of capacitors and microstrip lines for the matching circuit design results in a layout area of only 1.71 mm~2.This paper gives a detailed introduction to the basic theory and design method of broadband power amplifier.The design of the two broadband amplifiers mentioned in the article has also reached the expected level,and compared with the reference,this design achieves a larger bandwidth,while the chip size is significantly reduced.Therefore,this paper has a good reference value for the research of the subsequent broadband power amplifier.