Question

A Band Pass filter can be created by cascading two op amp circuits as shown in Figure 7. Your job is to create a MATLAB script to plot IVo(jw)/V(jw) in a log scale from 1 Hz to 100 MHz. 1 kS2 1 nF F 500 2 500 ? _vlt) Figure 7: Cascaded op amp circuit Hints: Use 100 points per decade so your script runs faster. For example 1Hz = 102-100 Hz ? a = 0 100 MHz-106-108 Hz-, b-8 We can see that we have 8 decades, which means we nod n = 8 x 100 = 800 points. In MATLAB, we do the following: f = logspace (a, b, n) logspace (0,8, 800) f f logspace (a, b, n) generates n points between decades 10 and 10 Questions: From your plot, what is the gain at ?-0 and oo? Explain.

Answer 1

code:

close all s-tf's) % for first op-amp GI is transfer function Rf-1e3: C-1e-6; R-500 G1 Rf/ (R+1/ (s*C)) % for second op-amp G2 is transfer function Rf-1e3: C-1e-9 R-500 % parallel combination is z G2-2/R % total system transfer function sys series (G1,G2) f-logspace (0, 8,800) bode (sys, f)

result:

Bode Diagram 20 10 10 20 50 S0 S0 101 102 103 106 10 108 104 Frequency (rad/s) 10 10

0.001s 0.0005 s+ 1 Continuous-time transfer function G2 1e-06 s 5e-13 s 2 + 5e-07 s Continuous-time transfer function Sys - 1e-09 s 2 2.5e-16 s 3 + 2.505e-10 s 2 + 5e-07 s Continuous-time transfer function