500MHz--3000MHz中频放大电路设计

摘要放大器采用 GaAs HBT 工艺，用两级结构实现高增益、高输出功率、高效率的目标。本文对功率放大器设计中的关键性问题分别进行了分析，并提出有效的解决措施。设计的自适应线性偏置电路为晶体管提供偏置电压的同时，还在高功率输入情况下补偿由此降低的功率管基极与发射极之间的电压，保持了放大器的偏置点不变并且抑制了增益压缩现象。偏置网络中的温度补偿电路利用 HBT 功率器件的热电负反馈特性，有效抑制了自热效应导致的直流偏置点的温漂现象和电流增益坍塌现象。通过在每个功率管的基极加上一个电阻电容并联稳定网络，消除了晶体管潜在不稳定因素，改善了电路的电学稳定性和热稳定性。第一级功率放大器采用共轭匹配设计以实现最大增益，第二级放大器则采用功率匹配原则按照最大输出功率设计。在版图设计和测试 PCB 板设计时，对寄生效应进行了充分的考虑。对 GaAs HBT 两级功率放大器芯片在 PCB 板上调试后的测试结果表明：放大器小信号功率增益为 50.6dB，成功实现了设计指标的要求。 60459
毕业论文关键词：功率放大器；GaAs HBT；自适应线性偏置电路；RC 并联稳定网络 Abstract The design of amplifier is based on GaAs HBT process technology, achieved the targets of high power gain, high output power and high efficient, with two-stage structure. In this paper, the key issues of power amplifier design are analyzed, and some effective solutions have been proposed. The adaptive linear bias circuit is designed for providing offset-voltage to the transistor, at the meantime, the reducing base-emitter voltage of the power tube due to the high power input is compensated, the amplifier's offset point is also maintained constant, and the phenomenon of gain compression is inhibited. In addition, the temperature drift phenomenon of the DC bias point and the current gain collapse phenomenon due to the self-heating effects is effectively inhibited by the temperature compensation circuit in the bias network using the thermoelectric negative feedback characteristics of HBT power devices. Through adding a RC parallel stable network in the base of each power tube, the potential instability of the transistor are eliminated, and the electrical and thermal stability of the circuit is improved. The maximum gain is realized by conjugate matching the first-stage power amplifier, the power matching principle is adopted according to the maximum output power design of the last stage amplifier power. Ultimately, the parasitic effect is considered sufficiently during the layout designing and PCB testing. The testing results of two-stage GaAs HBT power amplifier chip after the PCB commissioning show that the power gain of amplifier is 50.6 dB in the small signal, the specification requirements of design is successful implemented.
Key words: GaAs HBT; self-adaptation linear bias circuit; base stability resistor; RC parallel stable network

摘要 .. 1

Abstract . 2

第 1 章绪论 5

1.1 MMIC 功率放大器的发展前景 .. 5

1.2 GaAs HBT 功率器件的发展 .. 6

1.3 本论文的研究意义和主要内容 .. 7

第 2 章 MMIC 功率放大器设计技术及关键问题分析 .. 8

2.1 器件形式的选择 8

2.2 HBT 器件的工作原理 9

2.3 衬底材料的选择 . 10

2.4 MMIC 功率放大器的效率模式 11

2.5 MMIC 功率放大器的设计方法 13

2.5.1 小信号 S 参数设计法 14 500MHz--3000MHz中频放大电路设计:http://www.751com.cn/tongxin/lunwen_65934.html