摘要
针对接收机的接收通道杂散特性显著受混频杂散以及混频互调影响的问题,研制了一种双端恒阻滤波器,其具有在射频频率范围内不论在带内还是带外电压驻波比始终小于2的特点,可级联在混频器的输入输出端,将混频杂散以及混频互调信号吸收在该恒阻电路中,以降低混频杂散的幅度。以获取恒阻特性为原则,对该电路的结构进行了理论分析,推导得到双端恒阻滤波器的色散参数,并最终得到电路参数。最后,设计了一个截止频率为30MHz的双端恒阻低通滤波器,通带内外的电压驻波比(VSWR)均小于1.2,从而验证了该恒阻滤波器的可行性。
Due to the spurs of the receiver channel is affected by the mixer spurs and the mixer intermodulation,a two ports with constant impedence filter is designed.The(VSWR)is always smaller than 2,and it can be connected the input and output end of the mixer.The mixing spurious and the intermodulation signals can be absorped by the constant resistance circuit.In this paper,the dispersion parameters of the two-terminal constant-resistance filter are analyzed.Based on the principle of obtaining constant-resistance characteristics,the structure of the circuit is undertaked theoretical derivation,and the actual calculated parameters of the circuit are extracted.Finally,a consistent impedence low-pass filter with 30MHz cutoff frequency is designed,and the average VSWR in the inband and outband is smaller than 1.2.The results verify the feasibility of the filter structure.
出处
《大众科技》
2019年第10期6-9,18,共5页
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