一款适用于WCDMA标准的大动态范围SiGe HBT可变增益放大器设计

High Dynamic Range SiGe HBT Variable Gain Amplifier for WCDMA Applications

第三代移动通信标准WCDMA要求放大器增益可调,并且增益动态范围较大。根据这一要求给出了一种基于SiGeHBT具有高动态范围的可变增益放大器（VGA）设计。放大器为三级级联结构,第一级为输入缓冲级,第二级为增益控制级,最后为放大级。VGA的增益控制通过调整第二级的偏置实现。VGA在1.95 GHz频率下,在0～2.7 V增益控制电压变化下,具有44 dB增益变化范围,最大增益49 dB。在最大增益处最小噪声系数为2.584 dB,输入输出电压驻波比低于2,性能良好。

A high dynamic range linear-in-dB variable gain amplifier（VGA） using SiGe HBT devices for WCDMA applications is presented.The gain is achieved through three stages amplifiers.The first and the third stage is the normal amplify stage,and the second stage is the gain control stage.The gain control is implemented by adjusting the bias of the second amplifier.The VGA is driven by a 2.7 V power supply,and has a 44 dB linear gain control range varying from 4 dB to 49 dB when control voltage varies from 0 to 2.7 V.The maximum gain is 49 dB at the frequency of 1.95 GHz,the noise figure is 2.584 dB at maximum gain,input/output VSWRs keep below 2 and constant.