ASSIGNMENT: Active Filter Design Techniques
Refer to Chapter 6 in the text as needed.
Using the Fast, Practical Filter Design technique presented in section 6.3 design the following. Be sure to show all work for full credit.
Low-Pass Filter with critical frequency = 10kHz.
High-Pass Filter with critical frequency = 10kHz.
Narrow-Bandpass Filter with critical a band of 100kHz
Create a MultiSIM schematic of each of your designs. Provide a screenshot.
Perform a simulation of each design to demonstrate the filter behavior. Take a screenshot.
From your simulation and screenshot in the above step, what is the gain in dB at the critical frequency for the low-pass filter and the high-pass filter? What is the bandpass of the bandpass filter, and how did you determine it?
If you were to implement your high-pass filter in hardware, what considerations would you need to take into consideration? How would these considerations impact the performance and the extent to which you would meet specifications?
Be specific! Provide specific examples of the issues you would encounter based on your specific initial design and actions you would need to take to finalize your design. Is there anything you would have done differently to create your initial design in step 2 above if you had thought about an implementation in hardware from the beginning?
LAB:
The purpose of this lab is to demonstrate how to use Multisim in order to produce Bode Plots via AC Analysis. This plot will allow for a determination of the range of frequencies for which an op-amp circuit operates optimally. Students will make adjustments to external bias resistors to determine the relationship between gain and frequency in op-amp circuits.
Watch video Week 2 - Bode Plot
Construct an Active Filter (An Op-Amp configuration presented in the video) in Multisim and compute the gain of the amplifier (in db - Decibels) for the following combinations of RF and RG.
Perform AC Analysis to measure the gain of the amplifier (Use 5% resistor tolerances for simulation) and complete the table below:
| RF |
RG |
Calculated OpAmp Gain (in db) = Vout/Vin |
Measured OpAmp Gain (in db) = Vout/Vin |
| 2k? |
10k? |
|
|
| 2k? |
20k? |
|
|
| 2k? |
40k? |
|
|
| 10k? |
5k? |
|
|
| 20k? |
5k? |
|
|
| 40k? |
5k? |
|
|
Take the screen shots of bode plot for each of the above combinations of RF and RG.
For the Op-Amp Circuit, answer the following questions:
Does the measured values of the gain match the calculated values? If not, explain why they are different?
What is the cutoff frequency you measured from the simulation?
Based on the cut off frequency, what type of active filter is constructed in this lab?
From your measurements, explain how increase in RG affects the gain of the amplifier? How does bode plot change with increase in RG?
From your measurements, explain how increase in RF affects the gain of the amplifier? How does bode plot change with increase in RF?
What is the effect of resistor tolerance on the gain of the filter?
Verify all calculations from analysis and measurements from simulation. Save the results along with the table and paste the screen captures in the word document. Make sure to answer the questions.