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learn:courses:real-analog-chapter-11:start [2017/05/05 13:51] – [Checking the Frequency Response] Marthalearn:courses:real-analog-chapter-11:start [2023/02/08 12:37] (current) – external edit 127.0.0.1
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 ====== Real Analog: Chapter 11 ====== ====== Real Analog: Chapter 11 ======
--->Chapter 11 Downloads+[[{}/learn/courses/real-analog-chapter-10/start|Back to Chapter 10]] 
-  * {{ :learn:courses:real-analog-chapter-11:realanalog-circuits1-chapter11.pdf |Chapter 11 PDF}}+-->Chapter 11 Materials  
 +  * Lecture Material: 
 +    * {{ :learn:courses:real-analog-chapter-11:lecture29.ppt |Lecture 29 PowerPoint Slides}}: Frequency response examples, frequency response plots & signal spectra, filters 
 +    * {{ :learn:courses:real-analog-chapter-11:lecture30.ppt |Lecture 30 PowerPoint Slides}}: Checking frequency response results, time-to-frequency domain relations for first-order filters, Bode plots 
 +    * [[http://www.youtube.com/watch?v=X7VaMxhW2xY&list=PLDEC730F6A8CDE318&index=32&feature=plpp_video| Lecture 29 Video]] 
 +    * [[http://www.youtube.com/watch?v=lyqgIl8KM4M&list=PLDEC730F6A8CDE318&index=33&feature=plpp_video| Lecture 30 Video]] 
 +  * Chapter 11 Videos: 
 +    * [[http://www.youtube.com/watch?v=Bw6ahZ8znNU&list=PL170A01159D42313D&index=22&feature=plpp_video| Lab 11 Video 1]]: Introduction to Frequency Response: Using frequency response to estimate a circuit's behavior. A low-pass filter is used as an example to filter noise out of a sinusoidal signal. 
 +    * [[http://www.youtube.com/watch?v=R_7W6RuCUn0&list=PL170A01159D42313D&index=23&feature=plpp_video| Lab 11 Video 2]]: Practical Filters: Examples of low-pass filters are presented. The properties of passive vs. active filters are compared, especially relative to the effects of applying a "load" to the filter. 
 +    * [[http://www.youtube.com/watch?v=y-KQ2NMxws0&list=PL170A01159D42313D&index=24&feature=plpp_video| Lab 11 Video 3]]: Bode Plots: Bode plots and their creation using the Analog Discovery Network Analyzer. 
 +  * {{ :learn:courses:real-analog-chapter-11:real-analog-chapter-11.pdf | Chapter 11 Complete PDF}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p2p1.pdf |Lab 11.2.1}}     * {{ :learn:courses:real-analog-chapter-11:lab11p2p1.pdf |Lab 11.2.1}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p2p1_worksheet.docx |11.2.1 Worksheet}}+      * {{ :learn:courses:real-analog-chapter-11:lab11p2p1_worksheet.docx |Worksheet 11.2.1}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p3p1.pdf |Lab 11.3.1}}     * {{ :learn:courses:real-analog-chapter-11:lab11p3p1.pdf |Lab 11.3.1}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p3p1_worksheet.docx |11.3.1 Worksheet}}+      * {{ :learn:courses:real-analog-chapter-11:lab11p3p1_worksheet.docx |Worksheet 11.3.1}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p3p2.pdf |Lab 11.3.2}}     * {{ :learn:courses:real-analog-chapter-11:lab11p3p2.pdf |Lab 11.3.2}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p3p2_worksheet.docx |11.3.2 Worksheet}}+      * {{ :learn:courses:real-analog-chapter-11:lab11p3p2_worksheet.docx |Worksheet 11.3.2}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p3p3.pdf |Lab 11.3.3}}     * {{ :learn:courses:real-analog-chapter-11:lab11p3p3.pdf |Lab 11.3.3}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p3p3_worksheet.docx |11.3.3 Worksheet}}+      * {{ :learn:courses:real-analog-chapter-11:lab11p3p3_worksheet.docx |Worksheet 11.3.3}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p3p4.pdf |Lab 11.3.4}}     * {{ :learn:courses:real-analog-chapter-11:lab11p3p4.pdf |Lab 11.3.4}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p3p4_worksheet.docx |11.3.4 Worksheet}}+      * {{ :learn:courses:real-analog-chapter-11:lab11p3p4_worksheet.docx |Worksheet 11.3.4}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p3p5.pdf |Lab 11.3.5}}     * {{ :learn:courses:real-analog-chapter-11:lab11p3p5.pdf |Lab 11.3.5}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p3p5_worksheet.docx |11.3.5 Worksheet}}+      * {{ :learn:courses:real-analog-chapter-11:lab11p3p5_worksheet.docx |Worksheet 11.3.5}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p4p1.pdf |Lab 11.4.1}}     * {{ :learn:courses:real-analog-chapter-11:lab11p4p1.pdf |Lab 11.4.1}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p4p1_worksheet.docx |11.4.1 Worksheet}}+      * {{ :learn:courses:real-analog-chapter-11:lab11p4p1_worksheet.docx |Worksheet 11.4.1}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p4p2.pdf |Lab 11.4.2}}     * {{ :learn:courses:real-analog-chapter-11:lab11p4p2.pdf |Lab 11.4.2}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p4p2_worksheet.docx |11.4.2 Worksheet}}+      * {{ :learn:courses:real-analog-chapter-11:lab11p4p2_worksheet.docx |Worksheet 11.4.2}}
     * {{ :learn:courses:real-analog-chapter-11:lab11p4p3.pdf |Lab 11.4.3}}     * {{ :learn:courses:real-analog-chapter-11:lab11p4p3.pdf |Lab 11.4.3}}
-      * {{ :learn:courses:real-analog-chapter-11:lab11p4p3_worksheet.docx |11.4.3 Worksheet}} +      * {{ :learn:courses:real-analog-chapter-11:lab11p4p3_worksheet.docx |Worksheet 11.4.3}}
   * {{ :learn:courses:real-analog-chapter-11:realanalog-exercisesolutions-chapter11.pdf |Exercise Solutions}}: Chapter 11 exercise solutions   * {{ :learn:courses:real-analog-chapter-11:realanalog-exercisesolutions-chapter11.pdf |Exercise Solutions}}: Chapter 11 exercise solutions
   * {{ :learn:courses:real-analog-chapter-11:homework11.docx |Homework}}: Chapter 11 homework problems   * {{ :learn:courses:real-analog-chapter-11:homework11.docx |Homework}}: Chapter 11 homework problems
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 <-- <--
  
-====== 11. Introduction and Chapter Objectives ======+===== 11. Introduction and Chapter Objectives =====
 In section 10.6, we saw that a system’s frequency response provided a steady-state input-output relationship for a system, as a function of frequency. We could apply this frequency response to the phasor representation of the input signal in order to determine the system’s steady-state sinusoidal response – we simply evaluated the frequency response at the appropriate frequencies to determine the effect of the system on the input sinusoids. This approach had the potential for simplifying our analysis considerably, particularly for the case in which the input signal contained multiple sinusoids with different frequencies. In section 10.6, we saw that a system’s frequency response provided a steady-state input-output relationship for a system, as a function of frequency. We could apply this frequency response to the phasor representation of the input signal in order to determine the system’s steady-state sinusoidal response – we simply evaluated the frequency response at the appropriate frequencies to determine the effect of the system on the input sinusoids. This approach had the potential for simplifying our analysis considerably, particularly for the case in which the input signal contained multiple sinusoids with different frequencies.
  
-In [[https://reference.digilentinc.com/learn/courses/real-analog-chapter-10/start|Chapter 10]], the signals we considered consisted only of individual sinusoids. It is more useful, however, in some ways to think in terms of the inputs and outputs of the system as functions of frequency, in the same way in which we considered the frequency response of the system to be a function of frequency in section 10.6. We can then perform our analysis of the system entirely in terms of the frequencies involved. This leads to the use of the system’s frequency response directly as a design and analysis tool. In many cases, this means that the actual time- domain behavior of the system or signal is of limited interest (or in some cases, not considered at all). Some examples of frequency domain analyses are:+In [[/learn/courses/real-analog-chapter-10/start|Chapter 10]], the signals we considered consisted only of individual sinusoids. It is more useful, however, in some ways to think in terms of the inputs and outputs of the system as functions of frequency, in the same way in which we considered the frequency response of the system to be a function of frequency in section 10.6. We can then perform our analysis of the system entirely in terms of the frequencies involved. This leads to the use of the system’s frequency response directly as a design and analysis tool. In many cases, this means that the actual time- domain behavior of the system or signal is of limited interest (or in some cases, not considered at all). Some examples of frequency domain analyses are:
   - //Determining dominant sinusoidal frequency components in a measured signal//. Complex signals can often be represented as a superposition of several sinusoidal components with different frequencies. Identifying sinusoidal components with large amplitudes (the so-called dominant frequencies) can help with many design problems. One application of this is in the area of combustion instability – combustion processes in rocket engines can become unstable due to a variety of reasons, any of which can result in catastrophic failure of the engine. The type of instability which occurs is generally linked to a particular frequency; identification of the frequency of the pressure oscillations associated with the combustion instability is generally the first step in determining the cause of the instability.   - //Determining dominant sinusoidal frequency components in a measured signal//. Complex signals can often be represented as a superposition of several sinusoidal components with different frequencies. Identifying sinusoidal components with large amplitudes (the so-called dominant frequencies) can help with many design problems. One application of this is in the area of combustion instability – combustion processes in rocket engines can become unstable due to a variety of reasons, any of which can result in catastrophic failure of the engine. The type of instability which occurs is generally linked to a particular frequency; identification of the frequency of the pressure oscillations associated with the combustion instability is generally the first step in determining the cause of the instability.
   - //Designing systems to provide a desired frequency response//. Audio components in stereo systems are generally designed to produce a desired frequency response. A graphic equalizer, for example, can be used to boost (or amplify) some frequency ranges and attenuate other frequency ranges. When adjusting the settings on an equalizer, you are essentially directly adjusting the system’s frequency response to provide a desired system response.   - //Designing systems to provide a desired frequency response//. Audio components in stereo systems are generally designed to produce a desired frequency response. A graphic equalizer, for example, can be used to boost (or amplify) some frequency ranges and attenuate other frequency ranges. When adjusting the settings on an equalizer, you are essentially directly adjusting the system’s frequency response to provide a desired system response.
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 {{ :learn:courses:real-analog-chapter-11:chapter11t.png |Example image 2.}} {{ :learn:courses:real-analog-chapter-11:chapter11t.png |Example image 2.}}
  
-As $\omega \rightarrow 0$, the circuit becomes a voltage divider, and $v_{out} = \frac{3k \Omega}{2k \Omega + 3k \Omega} \cdot v_{in}$, so that the circuit;s gain is $\frac{3}{5}$. As $\omega \rightarrow \infty$, $v_{out}$ is measured across a short circuit, and the gain is zero.+As $\omega \rightarrow 0$, the circuit becomes a voltage divider, and $v_{out} = \frac{3k \Omega}{2k \Omega + 3k \Omega} \cdot v_{in}$, so that the circuit's gain is $\frac{3}{5}$. As $\omega \rightarrow \infty$, $v_{out}$ is measured across a short circuit, and the gain is zero.
  
  
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 {{ :learn:courses:real-analog-chapter-11:chapter11bn.png?nolink |Example image 1.}} {{ :learn:courses:real-analog-chapter-11:chapter11bn.png?nolink |Example image 1.}}
  
-The frequency response for this circuit is $H(j \omega) = \frac{1}{j \omega + 2}$. Therefore, the cuttof frequency is $\omega_c=2$ rad/sec and the gain in decibels at low frequencies is $|H(j0)|_{dB} = 20log_{10} \left( \frac{1}{2} \right) \approx -6dB$. Thus, the straight-line magnitude response is -6dB below the cutoff frequency and decreases by 20dB/decade above the cutoff frequency. The straight-line phase response is $0^{\circ}$ below 0.2rad/sec, $-90^{\circ}$ above 20 rad/sec and a straight line between these frequencies. The associated plots are shown below.+The frequency response for this circuit is $H(j \omega) = \frac{1}{j \omega + 2}$. Therefore, the cutoff frequency is $\omega_c=2$ rad/sec and the gain in decibels at low frequencies is $|H(j0)|_{dB} = 20log_{10} \left( \frac{1}{2} \right) \approx -6dB$. Thus, the straight-line magnitude response is -6dB below the cutoff frequency and decreases by 20dB/decade above the cutoff frequency. The straight-line phase response is $0^{\circ}$ below 0.2rad/sec, $-90^{\circ}$ above 20 rad/sec and a straight line between these frequencies. The associated plots are shown below.
  
 {{ :learn:courses:real-analog-chapter-11:chapter11bo.png?nolink |Example image 2.}} {{ :learn:courses:real-analog-chapter-11:chapter11bo.png?nolink |Example image 2.}}
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 {{ :learn:courses:real-analog-chapter-11:chapter11bq.png?nolink |Exercise image 2.}} {{ :learn:courses:real-analog-chapter-11:chapter11bq.png?nolink |Exercise image 2.}}
  
 +
 +[[{}/learn/courses/real-analog-chapter-10/start|Back to Chapter 10]]
 +[[{}/learn/courses/real-analog-chapter-12/start|Go to Chapter 12]]