Lab 4 - EE 420L 

Mario Valles

February 27, 2015

Op-amps II, gain-bandwidth product and slewing

• Estimate, using the datasheet, the bandwidths for non-inverting op-amp topologies having gains of 1, 5, and 10.
• |G|BW = 1.3MHz
• |G| = 1 --> BW = 1.3MHz/1 = 1.3 MHz
• |G| = 5 --> BW = 1.3MHz/5 =  260 KHz
• |G| = 10 --> BW = 1.3 MHz/10 = 130 KHz
• Experimentally verify these estimates assuming a common-mode voltage of 2.5 V.
• Your report should provide schematics of the topologies you are using for experimental verification along with scope pictures/results.
• Associated comments should include reasons for any differences between your estimates and experimental results.

• The next picture show how the experimental results
• |G| = 1

• Here We show the frequency when the output amplitude started to diminish which around 1.012MHZ. This is 300Khz under what we expected
• |G| = 5
• 
• The output voltage started going down in frequency at 220.1 Khz which about 40 kHz difference of what we expected
• G| = 10
• 
• The output voltage started going down in frequency at 220.1 Khz which about 40 kHz difference of what we expected
• Repeat these steps using the inverting op-amp topology having gains of -1, -5, and -10. 
• 
  
• |G|BW = 1.3MHz
• |G| = -1 --> BW = 1.3MHz/2 = 650 kHz
• |G| = -5 --> BW = 1.3MHz/6 =  216 KHz
• |G| = -10 --> BW = 1.3 MHz/11 = 118 KHz
• G| = -1

• the outpu voltage here is 664.8 Khz which is 14.8 kHz more than is calculated 
• |G| = -5
• 
• the outpu voltage here is 216.7Khz which is .2 kHz less than is calculated 
• |G| = -10
• 
• The resason is that the op-amp have parameter that changes the output in real life, here we show when the amplified output started to decrease in magnitude.
• Design two circuits for measuring the slew-rate of the LM324. One circuit should use a pulse input while the other should use a sinewave input.
• Provide comments to support your design decisions.
• Comment on any differences between your measurements and the datasheet’s specifications.
• 
• The reason that we used this topology is because we wanted to know what happened when the gain is one
• 
• 
  
• The reason we used this topology was to see how is it when we have only the difference of input voltages being amplified
• The datasheet show that the slew rate is .4V/µs however whe got 0.35 V/µs which is close the reason is because op-amps are not ideal and also we use differen set than what the data sheet used.