论文部分内容阅读
本文说明两种Q值可变的带通滤波器,两者都使用一个单级固定增益的放大器,和少量无源元件;并都具有高稳定的Q值和谐振频率。为评价其性能和灵敏度,说明了电路的数学推导和测试结果。数学推导对于二阶带通滤波器,电压传输画数的一般表示式为: H(S)=e_o(s)/e_i(s)=K_o(ω_o/Q)S/(S~2+(ω_o/Q)S+ω_o~2)式中 K_o=谐振点的电压增益ω_o=谐振频率(弧度/秒) Q=谐振频率与-3分贝带宽之比(ω_o/BW) 图1和2所示电路中,列有上述常数与R,C和放大器增益K的函数关系式。放大器增益是由反馈电阻R_1和R_2决定的,即R_2=(K-1)R_1。由于增益取决于Q值,所以
This article shows two variable Q-band pass filters, both using a single-stage, fixed-gain amplifier with a small number of passive components; all with high Q values and resonant frequencies. To evaluate its performance and sensitivity, the mathematical derivation and test results of the circuit are described. Mathematical derivation For the second-order band-pass filter, the general expression for the voltage transfer plot is: H (S) = e_o (s) / e_i (s) = K_o (ω_o / Q) S / (S ~ 2 + (ω_o / Q = S + ω_o ~ 2 where K_o = voltage gain at the resonance point ω_o = resonant frequency in radian / second Q = ratio of resonant frequency to -3 dB bandwidth (ω_o / BW) In the circuit shown in Figures 1 and 2 , There is a function of the above constant as a function of R, C and amplifier gain K. Amplifier gain is determined by the feedback resistors R_1 and R_2, that is R_2 = (K-1) R_1. Since the gain depends on the Q value,