针对传统恒定建立时间数字AGC(自动增益控制)环路实现方式复杂、成本高的问题,基于AGC环路的对数模型,推导出AGC环路建立时间恒定的条件,提出采用线性放大器实现恒定建立时间AGC环路的方法,该方法能够在数字实现上省去传统方式的指数运算单元,降低了实现复杂度和成本.另外,对于非突跳或突跳幅度较小输入信号,利用输出信号平方检测代替对数功率检测,省去传统方式的对数运算单元,进一步降低了实现复杂度和成本.通过上述2种改进,提出了一种简单的恒定建立时间数字AGC环路设计方法.Simulink仿真证明了该设计方法的正确性.该方法应用于无线数字接收机中,能够简化设计,节约成本.%Based on the logarithmic model of AGC (Automatic Gain Control),conditions for keeping constant settling time of AGC loops have been derived and a method using a linear amplifier to achieve a constant settling time AGC loop is proposed to simplify the design and reduce the cost of conventional constant settling time digital AGC loops.The exponential computing unit of the conventional method is eliminated,thus reducing the complexity and cost of implementation.Furthermore,square detection is used instead of the conventional logarithmic power detection for non-sudden jump or slight sudden jump input signals,and this lowers the cost further.Based on the two improvements,a simplified design method is proposed for constant settling time digital AGC loops.Correctness of the design method is proved by the simulation results.The method can be used in wireless digital receivers to simplify design and to save cost.
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