OPAMP Circuits - Comparators and Zero Crossing Detectors

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OPAMP CircuitsPART -II

• CEC

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Contents

• Zero Crossing Detector.
• Level Comparator.
• Current to Voltage Converter.
• Voltage to Current Converter.

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Zero Crossing Detector

• Open Loop Configuration, no feedback.
• Open loop Gain of OPAMP very high.
• Output Saturation even with a very small input.
• Inverting and Noninverting Configurations.
• Comparison against zero volt reference, one input
  grounded.
• Sinewave to square wave converter.

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Inverting Zero Crossing Detector
Diodes for protection against excessive
amplitudes.
Input applied to inverting terminal. Noninverting
terminal grounded (zero reference). Negative
saturation when input gt 0 V. Positive saturation
when input lt 0 V.
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Noninverting Zero Crossing Detector
Inverting input grounded. Input to noninverting
terminal. Positive saturation when Vin gt 0
V. Negative saturation when Vin lt 0V.
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Inverting Comparator
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Inverting Comparator
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Noninverting Comparator
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Noninverting Comparator
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Noninverting Comparator
Reference Voltage derived from power supply
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Inverting Comparator
Reference Voltage derived from output voltage
Schmitt Trigger.
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Comparator
Open Loop Configuration
Can convert any arbitrary input to square wave.
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Current to Voltage Converter
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Current to Voltage Converter

iin
Hence Vo -IinRf
Vin and R1 can be replaced by a current source iin
Vin and R1 replaced by a current source
I/V Converter
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Voltage to Current Converter
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Thank You