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university:courses:electronics:electronics-lab-13a [30 Oct 2017 04:53] – Trecia Agoylouniversity:courses:electronics:electronics-lab-13a [25 Jun 2020 22:07] – external edit
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-====== Activity 13A. Amplifier Output Stages ======+====== Activity: Amplifier Output Stages ======
  
 ===== Objective: ===== ===== Objective: =====
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 ===== Procedure: ===== ===== Procedure: =====
-The waveform generator, W1, should be configured for a 1 KHz sine wave with 6.0 volt amplitude peak amplitude and 0 offset. Using scope channel 1 to observe the input at W1 and scope channel 2 to observe the output of the amplifier at R<sub>L</sub>.+The waveform generator, W1, should be configured for a 1 KHz sine wave with 6.0 volt amplitude peak-to-peak and 0 offset. Using scope channel 1 to observe the input at W1 and scope channel 2 to observe the output of the amplifier at R<sub>L</sub>.
 {{ :university:courses:electronics:a13a_f3_wf.png? |}} {{ :university:courses:electronics:a13a_f3_wf.png? |}}
  
 <WRAP centeralign> Figure 3 Push - Pull Output stage Waveforms </WRAP> <WRAP centeralign> Figure 3 Push - Pull Output stage Waveforms </WRAP>
  
-Next, apply power and adjust the waveform generator so that W1 is a 100 Hz triangle wave with 0V offset and 3.0 V amplitude values. Use the oscilloscope in the x-y mode to observe the voltage-transfer curve of the circuit. +Next, apply power and adjust the waveform generator so that W1 is a 100 Hz triangle wave with 0V offset and 3.0 V amplitude peak-to-peak. Use the oscilloscope in the x-y mode to observe the voltage-transfer curve of the circuit. 
  
 {{ :university:courses:electronics:a13a_f4_tc.png?400 |}} {{ :university:courses:electronics:a13a_f4_tc.png?400 |}}
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 • Starting with the amplitude = 0 V, gradually increase it until you just begin to see a signal on scope channel 2 appear at the output. For what range of amplitude values of W1 can we say that both BJT's are essentially off? Confirm this by observing the voltages of the current-sensing resistances R<sub>1</sub> and R<sub>2</sub>. • Starting with the amplitude = 0 V, gradually increase it until you just begin to see a signal on scope channel 2 appear at the output. For what range of amplitude values of W1 can we say that both BJT's are essentially off? Confirm this by observing the voltages of the current-sensing resistances R<sub>1</sub> and R<sub>2</sub>.
  
-• Raise W1 to 6.0V amplitude value, and record the amplitude of the output waveform as well as the collector currents of the BJTs, which can be found via Ohm's law from the voltages across R<sub>1</sub> and R<sub>2</sub>, and justify your findings in terms of circuit operation and the given component values.+• Raise W1 to 6.0V amplitude peak-to-peak value, and record the amplitude of the output waveform as well as the collector currents of the BJTs, which can be found via Ohm's law from the voltages across R<sub>1</sub> and R<sub>2</sub>, and justify your findings in terms of circuit operation and the given component values.
  
-• Repeat, but with W1 raised a 10.0V amplitude value; and comment.+• Repeat, but with W1 raised a 10.0V amplitude peak-to-peak value; and comment.
  
 Simulate the circuit of figure 1 using QUCS, compare with your lab findings, and justify any differences. Simulate the circuit of figure 1 using QUCS, compare with your lab findings, and justify any differences.
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 ===== Procedure: ===== ===== Procedure: =====
-The waveform generator, W1, should be configured for a 1 KHz sine wave with 6.0 volt amplitude peak amplitude and 0 offset. Using scope channel 1 to observe the input at W1 and scope channel 2 to observe the output of the amplifier at R<sub>L</sub>.+The waveform generator, W1, should be configured for a 1 KHz sine wave with 6.0 volt amplitude peak-to-peak and 0 offset. Using scope channel 1 to observe the input at W1 and scope channel 2 to observe the output of the amplifier at R<sub>L</sub>.
 {{ :university:courses:electronics:a13a_f7_wf.png? |}} {{ :university:courses:electronics:a13a_f7_wf.png? |}}
  
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 ===== Procedure: ===== ===== Procedure: =====
-The waveform generator, W1, should be configured for a 1 KHz sine wave with 6.0 volt amplitude peak amplitude and 0 offset. Using scope channel 1 to observe the input at W1 and scope channel 2 to observe the output of the amplifier at R<sub>L</sub>.+The waveform generator, W1, should be configured for a 1 KHz sine wave with 6.0 volt amplitude peak-to-peak and 0 offset. Using scope channel 1 to observe the input at W1 and scope channel 2 to observe the output of the amplifier at R<sub>L</sub>.
 {{ :university:courses:electronics:a13a_f10_wf.png? |}} {{ :university:courses:electronics:a13a_f10_wf.png? |}}
  
 <WRAP centeralign> Figure 10 Emitter Follower zero-crossing distortion elimination Waveforms </WRAP> <WRAP centeralign> Figure 10 Emitter Follower zero-crossing distortion elimination Waveforms </WRAP>
 +
 +** Lab Resources:**
 +  * LTSpice files: [[downgit>education_tools/tree/master/m2k/ltspice/amp_out_stg_ltspice | amp_out_stage_ltspice]]
  
  
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 Using your scope input, measure Vout as well as the voltage across R<sub>3</sub> and R<sub>4</sub> for the following DC values of Vin: -5 V, -4 V, -3 V, ... 0 V, ... , +4 V, +5 V. Then, tabulate Vout and the current in R<sub>L</sub> as well as the collector currents of Q<sub>2</sub> and Q<sub>4</sub> and comment. Use the offset of the waveform generator to set the DC value with the amplitude set to 0V. Using your scope input, measure Vout as well as the voltage across R<sub>3</sub> and R<sub>4</sub> for the following DC values of Vin: -5 V, -4 V, -3 V, ... 0 V, ... , +4 V, +5 V. Then, tabulate Vout and the current in R<sub>L</sub> as well as the collector currents of Q<sub>2</sub> and Q<sub>4</sub> and comment. Use the offset of the waveform generator to set the DC value with the amplitude set to 0V.
  
-Measure the input impedance by inserting a 10K? resistor in series with the signal generator (between W1 and the bases of Q<sub>1</sub>and Q<sub>3</sub>) and connecting the channel 1 differential scope inputs, 1+ , 1- across the 10K? resistor. Capture the input current vs. the input voltage and calculate the input resistance from the slope of the curve. Justify your results based on the component values used in the circuit. How do your results compare to what you measured for the circuit in figure 5?+Measure the input impedance by inserting a 10KΩ resistor in series with the signal generator (between W1 and the bases of Q<sub>1</sub>and Q<sub>3</sub>) and connecting the channel 1 differential scope inputs, 1+ , 1- across the 10KΩ resistor. Capture the input current vs. the input voltage and calculate the input resistance from the slope of the curve. Justify your results based on the component values used in the circuit. How do your results compare to what you measured for the circuit in figure 5?
  
-Simulate the circuit of figure 3 using QUCS, compare with your lab findings, and justify any differences.+Simulate the circuit of figure 3 using LTSpice or ADIsimPE, compare with your lab findings, and justify any differences.
  
 +<WRAP round download>
 +**Resources:**
 +  * Fritzing files: [[downgit>education_tools/tree/master/m2k/fritzing/output-stages | output_stages]]
 +  * LTspice files: [[downgit>education_tools/tree/master/m2k/ltspice/output_stages_ltspice | output_stages_ltspice ]]
 +</WRAP>
 ==== For Further reading: ==== ==== For Further reading: ====
 Output Stages [[http://www.analog.com/static/imported-files/tutorials/MT-207.pdf|(MT-207)]]\\ Output Stages [[http://www.analog.com/static/imported-files/tutorials/MT-207.pdf|(MT-207)]]\\
 [[http://en.wikipedia.org/wiki/Push-pull_output|Push-Pull Outputs]] [[http://en.wikipedia.org/wiki/Push-pull_output|Push-Pull Outputs]]
 +
 +
  
 **Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]]** **Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]]**
university/courses/electronics/electronics-lab-13a.txt · Last modified: 24 Jan 2023 20:03 by Doug Mercer

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