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Op-Amp Gain Design Equation and Calculator

Instrumentation and Electrical Design

These calculators will determine the Gain and output voltage for both a Non-Inverting Op-Amp and an Inverting Op-Amp.

An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op-amp produces an output potential (relative to circuit ground) that is typically hundreds of thousands of times larger than the potential difference between its input terminals.

Non-Inverting Op-Amp Gain Calculator    
R 1 = Ohms    
R 2 = Ohms    
Gain =
(Rin + Rf)/Rin
Gain =      
Input Volts    
Output = Volts    
Op-Amp Negative Feedback        
Inverting Op-Amp Gain Calculator    
R 1 = Ohms    
R 2 = Ohms    
Gain = Rf/Rin      
Gain =      
Input Volts    
Output = Volts    

Op-amps may be classified by their construction:

  • discrete (built from individual transistors or tubes/valves )
  • IC (fabricated in an Integrated circuit ) ??? most common
  • hybrid

IC op-amps may be classified in many ways, including:

  • Military, Industrial, or Commercial grade (for example: the LM301 is the commercial grade version of the LM101, the LM201 is the industrial version). This may define operating temperature ranges and other environmental or quality factors.
  • Classification by package type may also affect environmental hardiness, as well as manufacturing options; DIP , and other through-hole packages are tending to be replaced by surface-mount devices .
  • Classification by internal compensation: op-amps may suffer from high frequency instability in some negative feedback circuits unless a small compensation capacitor modifies the phase and frequency responses. Op-amps with a built-in capacitor are termed " compensated ", or perhaps compensated for closed-loop gains down to (say) 5. All others are considered uncompensated.
  • Single, dual and quad versions of many commercial op-amp IC are available, meaning 1, 2 or 4 operational amplifiers are included in the same package.
  • Rail-to-rail input (and/or output) op-amps can work with input (and/or output) signals very close to the power supply rails.
  • CMOS op-amps (such as the CA3140E) provide extremely high input resistances, higher than JFET -input op-amps, which are normally higher than bipolar -input op-amps.
  • other varieties of op-amp include programmable op-amps (simply meaning the quiescent current, gain, bandwidth and so on can be adjusted slightly by an external resistor).
  • manufacturers often tabulate their op-amps according to purpose, such as low-noise pre-amplifiers, wide bandwidth amplifiers, and so on.


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