一款用于5 G功率放大器的分段线性温度补偿偏置电路

实现了一款用于功率放大器的具有温度补偿特性的偏置电路,首先通过正温度系数(PTAT)电流与负温度系数(NTAT)电流对功率放大器所需的偏置电流进行线性温度补偿,然后在线性补偿的基础上引入分段设计,实现分段线性温度补偿,保证全温范围内功率放大器增益线性化。同时通过分段电流舵型DAC灵活调整偏置电流的大小,将功率放大器偏置在合适工作点的同时降低开关噪声。该偏置电路采用Jazz 0.18μm SOI工艺实现。测试结果表明:在-30~30℃温度区间内,电流补偿斜率为14.9%;在30~90℃温度区间内,电流补偿斜率为29.6%,电流斜率的精度均在1.5%以内;室温下偏置电流的线性调整率为1.4%,输出偏置电流在20.2~1 022.0μA范围内可调。采用该偏置电路的一款功率放大器输出功率典型值为28dBm,误差矢量幅度(EVM)在-30~90℃温度区间内小于3%。

A Bias Circuit with Piecewise Linear Temperature Compensation for 5 G Power Amplifier

A bias circuit with temperature compensation for power amplifier was presented. Firstly, the bias current for power amplifier was compensated linearly by proportional-to-absolute temperature(PTAT) current and negative-to-absolute temperature(NTAT) current. And then, the piecewise design was introduced based on the linear compensation to achieve piecewise linear temperature compensation and make sure the gain linearity during the whole range of working temperature. Simultaneously, a segmented current steering with digital-to-analog converter(DAC) controlled bias current magnitude flexibly, provided suitable bias operation point for the power amplifier and reduced the switching noise. This bias circuit had been successfully fabricated by the Jazz 0.18 μm SOI technology. The experimental results show that the compensation current slope is 14.9% and 29.6% during the temperature from-30℃ to 30℃ and from 30℃ to 90℃, respectively. The accurate of current slope are both within 1.5%. Line regulation of the bias current is 1.4% under room temperature and the bias current can be adjusted from 20.2 μA to 1 022.0 μA. The typical output power of a power amplifier with the proposed bias circuit is 28 dΒm, and the error vector magnitude(EVM) is below 3% from-30℃ to 90℃.