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通过改进偏置网络改善二次谐波抑制的新
方法
郑运峰
*
作者简介:郑运峰(1985-09-09),男,高级射频工程师,射频功放及相关外围链路. E-mail:
eric_dayong@hotmail.com
(北京裕源大通科技股份有限公司) 5
摘要:非线性是放大器的典型特征,任何一款放大器产品在大信号情况下都存在着非线性行
为,这样导致输出信号不能完整的无失真的放大输入信号,进而引入其他频率分量。包括典
型的单音信号的谐波分量,多音信号的谐波分量和交调分量。大部分的应用场合这种交调分
量和谐波分量都被认为是有害的,必须加以抑制。对于交调分量的抑制有很多种方案,比如10
前馈技术,直接反馈技术,预失真技术等是公认的成熟技术,能够将交调产物抑制到指标范
围内。但是针对谐波的抑制目前没有较好的方案。在输出功率不大的情况下,通常在输出端
加低通或者带通滤波器抑制谐波幅度,且有一定的改善,弊端是任何滤波器都有功率损耗和
功率容量,这种情况使得产品的效率大大降低,同时限制了产品输出功率等级。本文就此问
题提出通过改变输出端偏置网络的表现形式来有效抑制二次谐波幅度 10dB 以上的新方法,15
此种形式的谐波抑制方法提升了产品效率,节约了产品设计尺寸,从某种程度上说不受功率
等级的限制,大大拓展了产品的可应用范围,拓展了新思路。
关键词:谐波;椭圆滤波;非线性
中图分类号:TN
20
New way degrade 2nd harmonics by changing output bias
circuit
zhengyunfeng
(Wellhead Stone Technology Co.,Ltd)
Abstract: Nonliearity is the main characteristics of power amplifier. Any amplifer behave 25
nonliearity in large signal,so the output amplified signal is not true to the original and with many
harmonics. This is include harmonics induce by single frequency and intermodulation induce by
multi frequency. It's a harmful products in most application for this harmonics and
intermodulaiton, and should be compressed. There are many ways of plan for compressed for
intermodulation like feed forward, feed back, and predistoration. These technics is well used in 30
moden telecommunications systems. But there seems no better ways control 2
nd
harmonics in
ouput signal. Commonly add band pass filter in PA output, the filter should be support rated
output power,ofcourse it will be degrade 2
nd
harmonics but only specify for lower level rated
output power, further more the insertion loss will degrade PA effienciy and add cost,the size of
filer also should be considered. According these issues raise my idea in changing PA output bias 35
circuits to compressed 2
nd
harmonics in its amplitude. The simulation results looks better change
more than 10dB for 2
nd
harmonics. This kinds of frame idea is a big direction and lead for
changing 2
nd
harmonics, rise efficiency, reduce size, doesn't limit by output power, anyway this
idea spread range of product application and lead the thinking in a new way.
Key words: Harmonics;Ellipitic Filter;Nonlinearity 40
0 引言
移动通信是当今通信领域内最为活跃、发展最为迅速的领域之一。早期的移动通讯主要
应用与军用设备,但是 70 年代中期以后,民用移动通信的迅猛发展,业务范围扩大,因此
频率资源变的十分宝贵
[1]
。
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