摘要
可变增益放大器是GPS接收机中的一个关键模块，它与反馈环路组成的自动增益控制电路为模／数转换器（ADC）提供恒定的信号功率。模拟信号控制增益的VGA增益连续变化，但是线性度较差。这里采用电阻形式的负反馈的放大器来设计一个0～30dB增益变化的中频可变增益放大器，VGA的增益精度并不取决于工艺、电压和温度等因素对电阻、MOS管开关的影响，增益误差在各个工艺角下都小于5％。基于0．18μm CMOS工艺的测试结果表明，带内纹波小于0．1dB，IIP3达到31dBm@0dB，功耗为3mA，其中包括直流偏移消除模块和CMOS源极跟随缓冲电路。因此，该放大器适合在接收机模拟前端使用。
The variable gain amplifier embedded in an automatic gain control loop is an essential component of GPS receiver. With the feedback loop,it constitutes the automatic gain control circuit for ADC to provide constant power signal. VGA gain controlled by analog signal has continuous change,but poor linearity. Resistive negative feedback amplifier is proposed to design a gain range of 0-30 dB intermediate frequency variable gain amplifier. Its gain accuracy nearly does not depend on factors of process,voltage and temperature influence on resistor and MOS switch,gain error less than 0.5% under all corners. Testing results based on 0.18 μm CMOS technical indicates that inband ripple is less than 0.1 dB,IIP3 is 31 dBm@0 dB, while dissipating 3 mA（containing DC-offset cancellation circuit and CMOS Source- Follower Buffer Circuit）. As a result, this amplifier is suitable for the use in analog front - end receiver.
出处
《现代电子技术》
2009年第12期4-6,9,共4页
Modern Electronics Technique
基金
上海市科委浦江人才计划资助(07pj14060)
关键词
可变增益放大器
电阻形式负反馈
增益精确
带内纹波
variable gain amplifier
resistive negative feedback
accurate gain
low in - band ripple
