Pyrothermal infrared detection circuit composed of OPA111

Pyrothermal infrared ray is an application of non-contact temperature measurement of objects through infrared rays radiated by the object. Since
the detected signal is very weak, the sensitivity of the pyrothermal infrared sensor must be very high and the noise must be very
small; similarly , also has very high requirements on the amplification circuit, and ordinary operational amplifiers cannot meet the requirements. The pyroheat infrared measurement circuit composed of OPA 111 is shown in the figure.     The structure of the circuit is like a general operational amplifier, except that the feedback resistor is very large (requiring a very large gain); the signal leads and the copper foil traces of the signal pins on the printed circuit board must be shielded. Because the gain of the amplifier is very large, external noise will cause interference if it is not shielded.