Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: of input voltages increases with increasing resistance. The unloaded condition is the equivalent of infinite resistance open circuit and has the largest range (97.9mV) and the 98Ω has a range of 37.9mV. The output resistance is approximately 56.76Ω. To calcule this a voltage division relation was setup. The output voltage with a load of 986.5Ω (5.04V) is equal to to the output voltage of no load (5.33V) times the ratio of the load resistance to the load resistance in series with the output resistance. Solving for the output resistance yields 56.76Ω. [Vout(loaded)=Vout(unloaded)*(Rload/(Rload + Routput))] Comments on Voltage Transfer Function - Open vs. Closed Loop: The differences in the open and closed loop responses lies in the linear range of the two voltage transfer functions. The open loop response has a a slope in the linear range of approximately ∞, while in the closed loop response the gain is 38.81 decibals. This results from the feedback network containing the a feedback resistor which is used to control the amount of gain yielded by the Op Amp. Lower resistance in the feedback network results in lower gain. Open loop Op Amps are not reliable amplifiers because a small voltage offset results in maximum gain. The closed loop Op Amps have controllable gain and allows the user to control the amplification of the incoming signal. The other major diffence is the sign of the slopes. The open loop response has a positive slope because the voltage sweep is applied to the non-inverting terminal, and the opposite for closed loop. Inverting Amplifier Test Circuit (AC) Inverting Amplifoer 1 kHz Waveforms Func.Generator: 50mV pk-pk, Sine Wave, zero offset, 1KHz Scope: DC coupling and Time Div 500microseconds (place 1 kHz closed loop waveforms here) G a in ( d B) |Vout/Vin| =92.96 Phase Shift = 180 ° ECE2100 Lab #4 - Operational Amplifier Circuits Page 3 of 4 Fall 2012 Inverting Amplifier Frequency Sweep(Note:Did not enable 50Ω load, Vout is apporx. half) Amplifoer : Bode Magni...
View Full Document

This note was uploaded on 01/22/2014 for the course ECE 2100 taught by Professor Kelley/seyler during the Fall '05 term at Cornell University (Engineering School).

Ask a homework question - tutors are online