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当选频放大器工作在频率很低的情况下,谐振回路往往应用RC网格.RC网格的形式很多,接在电路中的位置也各不相同.应用得最多效果最好的要推RC双T电桥了.利用RC双T电桥接在放大器负反馈电路中,当信号频率等于电桥的谐振频率时,反馈系数为零,因而放大器的放大倍数基本上等于不接双T电桥时的放大倍数.当信号频率偏离电桥谐振频率时,因有较大的负反馈存在,放大器的放大倍数迅速下降,故可获得很好的选频性能.由于晶体管的出现,上述选频放大器更可利用晶体管制作,获得体积小、耗电少而性能优良的选频放大器.本文拟介绍一个次音频低耗电的晶体管选频放大器.
The selected frequency amplifier work in the case of very low frequency, the resonant circuit often use the RC grid.RC grid in many forms, then the location of the circuit are also different.Application of the most effective to push the RC double T Bridge. The use of RC double T bridge connected to the amplifier negative feedback circuit, when the signal frequency is equal to the resonant frequency of the bridge, the feedback coefficient is zero, so the amplifier magnification is basically equal to not connect double T bridge amplification Multiples.When the signal frequency deviates from the resonant frequency of the bridge, due to the existence of a larger negative feedback, the amplifier’s rapid decline in amplification, it can get a good selection of frequency performance due to the transistor, the above selection amplifier is more available Transistor production, access to small size, low power consumption and excellent performance of the frequency selective amplifier.This article intends to introduce a sub-audio low-power transistor frequency selective amplifier.