Question

I need help with this. I am unfamiliar with Ltspice and want to make sure I am doing this right. Please be thorough with your explanations.

. Design a high pass filter (Fig. 1) which has a break point fo 1 kHz at 3dB below the midband level (the -3dB point) Uses a C01uF capacitor, and calculate the value for R Vout C 0.1uF、 Vin 5Vac OVdc 2. Use LTspice to perform an AC sweep of your designed circuit from 10Hz to 10kHz with 10 points per decade. Place a Voltage source on the schematic from the edit tab component tab right click on voltage source select - advanced sine. You will need to use 5 Vpeak 0 DC as your voltage source. Print out the AC sweep and label the frequency of the point on the plot that is 3dB below the midband level (the -3dB poitRun the AC sweep simulation. The graph the gain with a scale is in dB with the decade selection command, which is a 20 log scale, then add the gain trace VouTVs versus frequency. You do not need to add the scale factor of 20log(Vout/Vin) What type of filter? ans: 3. Exchange C with R (Fig. 2) and measure the voltage across C and Vin as you did above. Do the LTspice sweep and change the graph to dB as in 2 What type of filter? ans: Label and tum in both graphs Vin 0.1u OVdc

Answer 1

Given that f_b = 1/2 pi RC the expression for the 3 dB frequency is f_3 - dB = 1/2 pi RC 1 eq Now, substitute the values into the equation 1 f = 1 kHz C = 0.1 mu F 1 times 10^3 = 1/2 pi R (0.1 times 10^-6) R = 1591.549 R = 1.59kHz