Radiant-flux integrating circuit for the discrimination of an infrared photodetector signal

Abstract

A new principle is proposed for the design of an infrared photodetector signal discrimination circuit that operates by integrating the radiant flux and utilizes a pn junction fieldeffect transistor. A characteristic feature of the circuit is the capability of reducing the background signal to negligible levels. A calculation shows that a dopedsilicon IR photoresistor can be combined with the proposed signal discrimination circuit to obtain high photosensitivities. Experimental data confirm this conclusion and demonstrate the indicated feasibility of controlling the background signal. Moreover, the results of experiments show that the proposed IR photodetector model can also be used to achieve high detectivities, including situations where it operates in the integration mode and where it is irradiated by a beam of 4-MeV electrons at fluences up to 2.10⁻¹⁵ cm⁻.