. Special Purpose Amplifiers

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• . Special Purpose Amplifiers
• . Differential Amplifier
• . Schematic Diagram

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• . Operation

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• . With the polarities shown previously
• . On positive going signal, Base of Q1 becomes
  more () with respect to emitter gt FB Q1 ? gt
  ICQ1 ? gt VRC1 ? gt VCQ1 ? (less ). Since ICQ1
  ? gt IEQ1 ? (IE ? IC ? IB) gt VRE ? gt
  Emitter of Q2 becomes less (-) with respect to
  Base gt FBQ2 ? gt ICQ2 ? gt VRC2 ? gt VCQ2 ?
  (more ). Due to the polarities assigned by our
  voltmeter, the difference between Q1 and Q2 is
  becoming less gt VOUT ? (Negative Going).
• . On negative going signal, Base of Q1 becomes
  less () with respect to emitter gt FB Q1 ? gt
  ICQ1 ? gt VRC1 ? gt VCQ1 ? (more ). Since ICQ1
  ? gt IEQ1 ? (IE ? IC ? IB) gt VRE ? gt
  Emitter of Q2 becomes more (-) with respect to
  Base gt FBQ2 ? gt ICQ2 ? gt VRC2 ? gt VCQ2 ?
  (less ). Due to the polarities assigned by our
  voltmeter, the difference between Q1 and Q2 is
  becoming larger gt VOUT ? (Positive Going).

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• . With the resulting output achieved, it can be
  said that a positive going input on the base of
  Q1 caused VCQ1 to be inverted gt the base of Q1
  is called the Inverting Terminal. Since the
  positive going input caused VCQ2 to increase in a
  positive direction, the base of Q2 is called the
  Non-Inverting Terminal.
• . If my voltmeter leads were changed, the output
  of the amplifier would also change. The Inverting
  and Non-Inverting terminals would also change.

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• . Operational Amplifiers (OPAMPS)
• .Block Diagram (Basic)

OUTPUT
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• . Ideal OPAMP Characteristics
• . Infinite (?) Input Impedance
• Draws little or no current from source.
• . Zero Output Impedance
• . Infinite (?) Gain
• . Infinite (?) Frequency Response
• Constant gain over any range of input signal
  frequencies.

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• . Types of OPAMPS
• . Linear (Output is Proportional to Input)
• . Inverting

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• . Non - Inverting

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• . Summing

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• . Difference

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• . Non - Linear (Output is not Proportional to
  Input)
• . Comparator

VREF ATTACHED TO EITHER OR - TERMINALS
(EXAMPLE SHOWS OUTPUT WITH VREF CONNECTED TO THE
NON-INVERTING TERMINAL.) (WAVEFORM WOULD BE
INVERTED IF VREF WAS ATTACHED TO THE INVERTING
TERMINAL)
VOUT
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• . Differentiator

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• . Integrator