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university:courses:electronics:text:chapter-2 [31 Aug 2013 16:26] – [2: Introduction and Chapter Objectives] Doug Merceruniversity:courses:electronics:text:chapter-2 [06 Jun 2017 16:41] – [2.7 Inverting Summing Op Amp Stage] Doug Mercer
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 However, if the values of the resistors are too low, a great deal of current is required from the op amp output for proper operation. This causes excessive power dissipation in the op amp itself, which has many disadvantages. The increased dissipation leads to self-heating of the integrated circuit, which can cause a change in the dc characteristics of the op amp itself.  Also, the heat generated can eventually cause the junction temperature to rise above 150º C, the commonly accepted maximum limit for most semiconductors. The junction temperature is the temperature at the silicon chip itself. On the other end of the spectrum, if the resistor values are too high, there is an increase in noise and the susceptibility to parasitic capacitances, which can limit bandwidth and possibly cause instability and oscillation.     However, if the values of the resistors are too low, a great deal of current is required from the op amp output for proper operation. This causes excessive power dissipation in the op amp itself, which has many disadvantages. The increased dissipation leads to self-heating of the integrated circuit, which can cause a change in the dc characteristics of the op amp itself.  Also, the heat generated can eventually cause the junction temperature to rise above 150º C, the commonly accepted maximum limit for most semiconductors. The junction temperature is the temperature at the silicon chip itself. On the other end of the spectrum, if the resistor values are too high, there is an increase in noise and the susceptibility to parasitic capacitances, which can limit bandwidth and possibly cause instability and oscillation.    
    
-From a practical sense, resistors below 10 ? and above 1 M? are more difficult to produce, especially if precision resistors are required. +From a practical sense, resistors below 10 Ω and above 1 MegΩ are more difficult to produce, especially if precision resistors are required. 
    
 =====2.5 Inverting Op Amp Gain Derivation ===== =====2.5 Inverting Op Amp Gain Derivation =====
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 If all the input resistors R<sub>1</sub>, R<sub>2</sub>, ... R<sub>n</sub> are equal but not equal to R<sub>f</sub> then from the equation we can see that it can be simplified such that the output will be equal to the algebraic sum of the inputs times a common gain factor of -R<sub>f</sub>/R<sub>1</sub>. If all the resistors are made equal including R<sub>f</sub> then the output will be simply the negative sum of the inputs. If all the input resistors R<sub>1</sub>, R<sub>2</sub>, ... R<sub>n</sub> are equal but not equal to R<sub>f</sub> then from the equation we can see that it can be simplified such that the output will be equal to the algebraic sum of the inputs times a common gain factor of -R<sub>f</sub>/R<sub>1</sub>. If all the resistors are made equal including R<sub>f</sub> then the output will be simply the negative sum of the inputs.
  
-**Lab Activity 1. [[university:courses:electronics:electronics-lab-1|Simple Op Amps]]**+**ADALM1000 Lab Activity 1. [[university:courses:alm1k:alm-lab-1|Simple Op Amps]]**\\ 
 +**ADALM2000 Lab Activity 1. [[university:courses:electronics:electronics-lab-1|Simple Op Amps]]**\\ 
 +**ADALM2000 Lab Activity [[university:courses:alm1k:alm-lab-vectrosumamp|Summing Amplifier]]**
  
 =====2.8 The Differential Op Amp Stage  ===== =====2.8 The Differential Op Amp Stage  =====
university/courses/electronics/text/chapter-2.txt · Last modified: 06 Jun 2017 16:44 by Doug Mercer

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