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Introduction to Opamps

An opamp (operational amplifier) is widely used in analog electronics and capable of performing various mathematical operations such as:

  • Addition and subtraction
  • Multiplication and division
  • Integration and differentiation
  • Log and antilog

 

      These capabilities allow the opamp to be used in numerous applications including:

      • Audio and RF amplifiers
      • Filters and equalizers
      • Modulators
      • Oscillators

        Basic Characteristics

        Characteristic Ideal Opamp
        Real Opamp
        Input impedance
        Infinite
        M W
        Output Impedance
        Zero
        <100 W
        Bandwidth Infinite
        10 Mhz
        Open Loop Voltage Gain
        Infinite
        20 k - 2 M
        Noise Contribution
        Zero
        mV
        DC Output Offset
        Zero
        mV

        Two other very important characteristics, which derive from the above list are:

        • Opamp inputs draw no current
        • The voltage at the inverting and non-inverting inputs are equal