输出功率-3dBm的射频发射前端在802.11g中的应用

A 2.4 GHz,direct-conversion RF transmitter front-end with an up converter and PA driver is fabricated in a 0.13μm CMOS process for the reliable transmission of 54 Mb/s OFDM signals.The front-end output power is -3 dBm while the corresponding EVM is -27 dB which is necessary for the 802.1 1g standard of EVM at-25 dB. With the adopted gain control strategy the output power changes from -14.3 to -3.7 dBm with every step 0.8 dB (20%) which covers the gain variation due to working temperature and process.A power detector indicates the output power and delivers a voltage to the baseband to control the output power.     

一种基于锗硅双极CMOS工艺的多频段移动电视调谐器芯片

本文给出了一种应用于多频段移动电视调谐器的射频芯片的设计和测试结果。射频调协器由宽带射频前端电路,模拟基带电路,全集成的小数频率综合器和I2C数字接口电路组成。为了满足移动电视标准苛刻的临道抑制指标,同时兼顾低功耗、低成本的要求,本设计采用了带局部自动增益控制的直接下变频接收机方案。为进一步提高临道抑制的性能,基带频道选择滤波器采用了8阶椭圆有源RC的结构,具有阻带衰减高和过渡带极陡的特点。射频调协器芯片采用0.35 μm锗硅双极CMOS工艺制成,硅片面积为5.5 mm2。芯片采用3.0V单电源供电,消耗50mA电流。在CMMB应用中,系统灵敏度达到-97 dBm,临道抑制优于40 dB。     

带自动增益控制的射频前端在CMMB U/V频段接收器中的应用

-本篇文章提出一种带自动增益控制(AGC)和数字控制射频可变增益放大器(RFVGA)的射频前端结构。这种前端结构是应用在中国移动多媒体广播(CMMB)直接下变频接收器中的。RFVGA提供了50dB的增益范围,每一步增益变化为1.6dB。所采用的AGC策略可以改善在CMMB系统中很关键的邻道信号抑制。射频前端由低噪声放大器(LNA), RFVGA,混频器(mixer), 以及AGC 组成。在LNA工作在低增益模式,RFVGA工作在中等增益模式时,射频前端的输入三阶交调点(IIP3)可以达到4.9dBm;当LNA与RFVGA都工作在最高增益模式时,射频前端的双边带噪声系数(NFdsb)低于4dB。本文所展示的射频前端采用0.35μm BiCMOS 工艺制作,电源电压3V,消耗电流25.6mA。     

An RF front-end with an automatic gain control technique for a U/V band CMMB receiver

This paper presents a fully integrated RF front-end with an automatic gain control(AGC) scheme and a digitally controlled radio frequency varied gain amplifier(RFVGA) for a U/V band China Mobile Multimedia Broadcasting(CMMB) direct conversion receiver.The RFVGA provides a gain range of 50 dB with a 1.6 dB step. The adopted AGC strategy could improve immunity to adjacent channel signal,which is of importance for CMMB application.The front-end,composed of a low noise amplifier(LNA),an RFVGA,a mixer and AGC,achieves an input referred 3rd order intercept point(IIP3) of 4.9 dBm with the LNA in low gain mode and the RFVGA in medium gain mode,and a less than 4 dB double side band noise figure with both the LNA and the RFVGA in high gain mode.The proposed RF front-end is fabricated in a 0.35μm SiGe BiCMOS technology and consumes 25.6 mA from a 3.0 V power supply.