ENGR337 Lab 2020 Spring
Lab 3 Filters and Amplifiers
Name: Jesse Duran
Email: JIDuran@fortlewis.edu

1. Filters and Amplifiers

2. Introduction:
The purpose of this lab was to design low pass and high pass filters to filter out noise and DC offset respectively. Additionally these signals were amplifed using OpAmps and an instrument amplifer. The noisy singal was provided by a function generator and an ADC. The input and output signals were then compared on the osilloscope. The physical circuits were useful in applying the knowlege learned in lecture to a pracitcal application.

3. Materials and Methods

Materials

2x Analog-Digital Converter 0-5V

Tektronix Oscilloscope

458nF capacitor

4.7uF capacitor

1N4370 zener diode

560Ω resistor

100kΩ resitor

2x 10kΩ resistors

1NA128PA Instrument Amp

741 OpAmp

Tektronix Function Generator

 
4. Results:

Task 1:

Figure 1. 500 mVpp, 1Hz, 1V DC offset provided by function generator

Task 2:

Figure 2. DC offset removed using oscilloscopes AC Coupling

Task 3:

Figure 3: Noise added to signal from 3.3V ADC

Task 4:
R was found by solving the equation:

R was found to be 102kΩ. A 100kΩ resistor was used in the circuit

Figure 4. Lowpass filter added, noise removed from the signal

Task 5.
The lowpass filter's R was the same as task 5. The highpass' R was found to be 67.7kΩ by solving the equation:



Figure 5. High pass and lowpass filters added in. Noise and DC offset removed however, the signal is attenuated.

Task 6.

Figure 6. Op Amp cuts off upper end of signal due to low quality of componant.


Figure 7. 10V power on Op Amp allows for full swing of amplification


Figure 8. Using instrument amp we can amplify the signal while using 5V rail to rail.

5. Discussion
This lab took the concepts we have been learning in lecture and applied them to physical circuits. It illustrated how noise is introduced from the wall socket and the importance of quality of componants as well as how to work around them. The oscilloscope is a powerful tool for circuit analysis.