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(一) 引言减小各种类型的变频干扰是混频器设汁的关键问题,采用平衡混频器就是减小上述干扰的有效措施。据分析和实验可知,当采用单平衡混频电路时,组合干扰的频率分量可减少50％,如果用双平衡混频电路时,则干扰频率分量可减少75％,这是平衡混频电路的主要优点,也是被广泛采用的原因所在。在平衡混频器中,选用有源器件,不仅可以有高电平混频的能力,而且混频器本身具有增益,这样对提高接收机的有效灵敏度,降低噪声,减轻对中放增益的要求等
(A) Introduction Reducing various types of frequency interference is a key issue for mixer design juice, the use of balanced mixer is an effective measure to reduce the above interference. According to the analysis and experiment, we can see that the frequency components of the combined interference can be reduced by 50% when the single balanced mixer circuit is used. If the double balanced mixer circuit is used, the interference frequency component can be reduced by 75% The main advantages are also the reason why it is widely used. In the balanced mixer, the use of active devices, not only can have a high level of mixing ability, and the mixer itself has a gain, so to improve the receiver’s effective sensitivity, reduce noise and reduce the requirements of the amplifier Wait