Circuit layout for an infrared room surveillance detector
First Claim
1. An infrared space surveillance detector circuit comprising:
- means for sensing wherein said means for sensing is a pyroelement;
a detector stage with a high impedance operational amplifier configured as a current amplifier directly responsive to said means for sensing;
means for performing a threshold value comparison responsive to an output of said operational amplifier.
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Abstract
A circuit layout operating in the current mode for an infrared room surveillance detector includes a high impedance operational amplifier connected directly to a pyroelement used as an infrared sensor. This results in a high sensitivity detector circuit with a low noise component in the detector output signal and maintaining a high impedance detector circuit. The detector circuit has a constant amplification over a relatively broad frequency range. The reaction resistor of the operational amplifier is chosen to have a high impedance, preferably in a range higher than 1011 Ohm. It is advantageous to take the reference voltage required for the evaluation of the detector output signal from the operational amplifier, so that aside from the simplified circuit layout, no further structural parts capable of increasing the interference sensitivity of the detector circuit are required. To further increase the electromagnetic compatibility, the threshold value comparator stage may also be located in the detector housing.
83 Citations
9 Claims
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1. An infrared space surveillance detector circuit comprising:
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means for sensing wherein said means for sensing is a pyroelement; a detector stage with a high impedance operational amplifier configured as a current amplifier directly responsive to said means for sensing; means for performing a threshold value comparison responsive to an output of said operational amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification