自跟踪对数域滤波器的设计

Design of Self-tracking Log-Domain Filter

在LC梯形网络设计的基础上,提出一种流控自跟踪二阶滤波器的电路结构和实现方法.输入的电压信号先经放大电路处理后,再经限幅电路、整形电路及宽频频率电流转换电路组成的频率自跟踪电路,将放大的电压信号转换为电流信号,以该电流信号作为对数域滤波电路的偏置电流控制端间接调节滤波器的截止或中心频率,从而实现滤波频率对输入频率的自动跟踪.仿真实验结果表明,带通滤波器和低通滤波器的最高中心频率为30MHz,对输入频率的跟踪范围为1~30 MHz.仿真实验验证了该设计方法的有效性和可行性.

We presented a circuit structure and realization method of the current-controlled selftracking filter which based on the design of LC ladder network.The input voltage signal was firstly processed by the amplifying circuit,and then the frequency self-tracking circuit was composed of amplitude limiting circuit,shaping circuit and broadband frequency-current conversion circuit.The amplified voltage signal was converted into the current signal which was used as the bias current control end of the log domain filter circuit to adjust the cut-off frequency or central frequency of the filter.Therefore,frequency of the filter could automatically track the input signal frequency.Simulation experiment results show that the highest central frequency of the band-pass filter and low-pass filter is 30 MHz,and the tracking range of input frequency is from 1 MHz to 30 MHz.Simulation results verify the effectiveness and feasibility of the proposed method.