# Lab _03 Frequency Dependent Operational Amplifier Circuits.docx

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```					                                         Name: Daniel Bernard
Team Members: Benjamen Strobel and Jack Ladwig
ECE 2212
Lab #03 Frequency Dependent Operational Amplifier Circuits and Oscillators
Due: February 16, 2012
Lab Coordinator: Stan Burns
Lab TA: Sukriti Subedi

Abstract:

This lab consists of implementation and measurements via circuit designs for the following circuits:

active analog Low-Pass Filter (LPF), active analog High-Pass Filter (HPF), Wien Bridge Oscillator, and a Phase

Shift Oscillator. For the Low-Pass Filter, design and test using the given circuit, values for resistors and the

capacitor that would produce a 20 dB voltage gain with a corner frequency of 3 dB in the 3-5 kHz range. Gain

and Phase shifting should be measured using the oscilloscope, and a transient analysis should be produced via a

PSpice simulation of the circuit, using the same values as what was used to simulate the circuit on a breadboard.

Similar design plans should be implemented on a High-Pass Filter, Wien Bridge Oscillator, and Phase Shift

Oscillator.
Introduction:
This lab covers implementation of active analog Low-Pass Filter (LPF), active analog High-Pass Filter (HPF), Wien Bridge
Oscillator, and a Phase Shift Oscillator. The lab also requires the simulation of the circuits in PSpice, and an applied transient analysis.

Background:
In this lab we apply our knowledge of nodal analysis and voltage division, in addition to our understanding of gain calculations and
phase measurements.

Procedure:
Low-Pass Filter:
Design a low-pass filter using the circuit shown below with a             Low-                                       Pass Filter:
low-frequency voltage gain of 20 dB, and 3 dB corner
frequency between 3-5 kHz. Simulate and experimentally
verify the circuit.
Measure                 and        , and simulate.

High-Pass Filter:
Design a high-pass filter using the circuit shown below with a            High-Pass Filter:
high-frequency voltage gain of 20 dB, and 3 dB corner
frequency between 100 Hz-500 Hz. Simulate and
experimentally verify the circuit.
Measure                 and        , and simulate.

Wein Bridge Oscillator:
Construct the circuit shown below. Observe the waveform                   Wein Bridge Oscillator:
transient analysis.

Phase Shift Oscillator:
Construct the circuit shown below. Observe the waveform                   Phase Shift
transient analysis. Compare the frequency of operation to the
equation,             , and voltage gain by          .

Measurements and Analysis of Results:
Low-Pass Filter:
Oscilloscope                                                           PSpice
,                          ,              ,                      , tried

The Oscilloscope readings and PSpice transient analysis match.

High-Pass Filter:
Oscilloscope                                                                                          PSpice

,                        , chose

Wein Bridge Oscillator:
Oscilloscope

PSpice clipping
PSpice growth
The Oscilloscope and PSpice transient analysis match. Useful at a wide frequency range.
Frequency Input        Output       OP/IP       Phase       20Log10(OP/IP)
(Hz)         (V)       (V)
100          2.1       20.6         9.809524 -179.5         19.83296
500                        2.12          20.4            9.622642   -162                   19.66589
1000                       2.1           18.8            8.952381   -155                   19.03877
2000                       2.12          15              7.075472   -134                   16.99511
5000                       2.12          8.2             3.867925   -112                   11.74956

Voltage Gain                                            0
Phase
25
100       500    1000   2000   5000
Voltage Gain (dB)

20
-50
15
Phase (°)

10                                                                              -100

5
-150
0
100     500           1000       2000    5000
Frequency (Hz)                    Voltage Gain                     -200
Frequency (Hz)            Phase
The Wien Bridge Circuit gives positive gain.

Phase Shift Oscillator:
Oscilloscope                                                                                    PSpice

Effective at low frequency, and inverts the signal.
Frequency Input          Output      OP/IP        Phase                         20Log10(OP/IP)
(Hz)          (V)        (V)
100           2.16       1           0.462963 90                                -6.68908
500                            2.16          4.56          2.111111   105.5     6.490222
1000                           2.12          8.5           4.009434   111.1     12.06166
2000                           2.2           14.6          6.636364   130       16.4386
5000                           2.12          20.2          9.528302   159.7     19.58031

Voltage Gain                                        200                     Phase
25
20
150
Voltage Gain (dB)

15
Phase (°)

10                                                                  100
5
0                                                                   50
100     500         1000      2000    5000
-5
-10                                                                   0
Frequency (Hz)                     Voltage Gain                        100     500     1000   2000
Frequency (Hz)            Phase 5000

Summary and Conclusion:
From this lab we constructed circuits that maximized gain at high or low frequencies, and changed gain and phase based on
how far the input frequency was from the corner frequency.

```
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