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university:courses:electronics:electronics-lab-variable-gain-amplifier [09 Nov 2018 15:29] – [Further Reading] add LTSpice files Antoniu Miclaus | university:courses:electronics:electronics-lab-variable-gain-amplifier [03 Jan 2021 22:21] (current) – fix links Robin Getz |
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Consider the circuit schematic presented in Figure 1. | Consider the circuit schematic presented in Figure 1. |
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<WRAP centeralign> {{:university:courses:electronics:var_gain_amp_crl-sch.png|}} </WRAP> | <WRAP centeralign> {{ :university:courses:electronics:vctrl_amp_transistor.png|}} </WRAP> |
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<WRAP centeralign> Figure 1. Voltage control using transistor </WRAP> | <WRAP centeralign> Figure 1. Voltage control using transistor </WRAP> |
==== Procedure ==== | ==== Procedure ==== |
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Use the first waveform generator as source Vin to provide a 2V amplitude, 1 kHz sine wave excitation to the circuit. Use the second waveform generator for controlling the transistor, providing a 2V amplitude, 1Hz square wave excitation. Supply the op amp to +/- 5V from the power supply. Configure the scope so that the input signal is displayed on channel 1 and the output signal is displayed on channel 2. | Use the first waveform generator as source Vin to provide a 2V amplitude peak-to-peak, 1 kHz sine wave excitation to the circuit. Use the second waveform generator for controlling the transistor, providing a 2V amplitude, 1Hz square wave excitation. Supply the op amp to +/- 5V from the power supply. Configure the scope so that the input signal is displayed on channel 1 and the output signal is displayed on channel 2. |
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An animated plot is presented in Figure 3. | An animated plot is presented in Figure 3. |
Consider the circuit schematic presented in Figure 4. | Consider the circuit schematic presented in Figure 4. |
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<WRAP centeralign> {{:university:courses:electronics:var_gain_amp_pot2-sch.png?500|}} </WRAP> | <WRAP centeralign> {{ :university:courses:electronics:var_g_invert_amp_pot.png|}} </WRAP> |
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<WRAP centeralign> Figure 4. Variable Gain Inverting Amplifier using potetiometer </WRAP> | <WRAP centeralign> Figure 4. Variable Gain Inverting Amplifier using potetiometer </WRAP> |
==== Procedure ==== | ==== Procedure ==== |
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Use the first waveform generator as source Vin to provide a 2V amplitude, 1 kHz sine wave excitation to the circuit. Supply the op amp to +/- 5V from the power supply. Configure the scope so that the input signal is displayed on channel 1 and the output signal is displayed on channel 2. | Use the first waveform generator as source Vin to provide a 2V amplitude peak-to-peak, 1 kHz sine wave excitation to the circuit. Supply the op amp to +/- 5V from the power supply. Configure the scope so that the input signal is displayed on channel 1 and the output signal is displayed on channel 2. |
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By varying the value of the potentiometer, an animated plot is presented in Figure 6. | By varying the value of the potentiometer, an animated plot is presented in Figure 6. |
Consider the circuit schematic presented in Figure 7. | Consider the circuit schematic presented in Figure 7. |
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<WRAP centeralign> {{:university:courses:electronics:var_gain_amp_pot-sch.png?500|}} </WRAP> | <WRAP centeralign> {{ :university:courses:electronics:var_gain_inv_noninv.png|}} </WRAP> |
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<WRAP centeralign> Figure 7. Variable Gain Inverting/Non-Inverting Amplifier using potetiometer </WRAP> | <WRAP centeralign> Figure 7. Variable Gain Inverting/Non-Inverting Amplifier using potetiometer </WRAP> |
==== Procedure ==== | ==== Procedure ==== |
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Use the first waveform generator as source Vin to provide a 2V amplitude, 1 kHz sine wave excitation to the circuit. Supply the op amp to +/- 5V from the power supply. Configure the scope so that the input signal is displayed on channel 1 and the output signal is displayed on channel 2. | Use the first waveform generator as source Vin to provide a 2V amplitude peak-to-peak, 1 kHz sine wave excitation to the circuit. Supply the op amp to +/- 5V from the power supply. Configure the scope so that the input signal is displayed on channel 1 and the output signal is displayed on channel 2. |
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By varying the value of the potentiometer, an animated plot is presented in Figure 9. | By varying the value of the potentiometer, an animated plot is presented in Figure 9. |
===== Further Reading ===== | ===== Further Reading ===== |
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| <WRAP round download> |
**Lab Resources:** | **Lab Resources:** |
* Fritzing files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/fritzing/var_gain_amp_bb | var_gain_amp_bb]] | * Fritzing files: [[downgit>education_tools/tree/master/m2k/fritzing/var_gain_amp_bb | var_gain_amp_bb]] |
* LTspice files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/ltspice/var_gain_amp_ltspice | var_gain_amp_ltspice]] | * LTspice files: [[downgit>education_tools/tree/master/m2k/ltspice/var_gain_amp_ltspice | var_gain_amp_ltspice]] |
| </WRAP> |
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Some additional resources: | Some additional resources: |
* [[http://www.analog.com/en/analog-dialogue/articles/x-amp-45-db-500-mhz-variable-gain-amplifier.html|X-Amp™, A New 45-dB, 500-MHz Variable-Gain Amplifier (VGA) Simplifies Adaptive Receiver Designs]] | * [[adi>en/analog-dialogue/articles/x-amp-45-db-500-mhz-variable-gain-amplifier.html|X-Amp™, A New 45-dB, 500-MHz Variable-Gain Amplifier (VGA) Simplifies Adaptive Receiver Designs]] |
* [[http://www.analog.com/en/analog-dialogue/articles/reinvent-the-signal-generator.html|Two New Devices Help Reinvent the Signal Generator]] | * [[adi>en/analog-dialogue/articles/reinvent-the-signal-generator.html|Two New Devices Help Reinvent the Signal Generator]] |
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**Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]]** | **Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]]** |