写出二阶有源滤波器的幅频特性的MATLAB代码

clc;
clear all;
close all;

%定义二阶有源滤波器的参数
R1 = 5e3;
R2 = 5e3;
R3 = 5e3;
R4 = 10e3;
C1 = 1e-9;
C2 = 1e-9;
A = 2;

%计算二阶有源滤波器的传递函数
s = tf('s');
H = A*(1/(R1*R2*C1*C2*s^2 + (R1*C1+R2*C1+R2*C2)*s + 1));

%绘制幅频特性曲线
w = logspace(1,6,1000);
[mag,phase] = bode(H,w);
magdB = 20*log10(mag);
figure(1);
semilogx(w,magdB,'LineWidth',2);
grid on;
xlabel('\omega (rad/s)');
ylabel('|H(j\omega)| (dB)');
title('二阶有源滤波器的幅频特性');