LOW-COST AND MINIMAL-CONDITIONING INTERFACE FOR A PBSE PHOTOCONDUCTORARRAY

A low-cost conditioning structure for PbSe photoconductor arrays with few components is described, We use a PbSe array of 64 pixels in a sim ultaneous atmospheric pollutant detector of several gases, The sensor system is based on infrared optical absorption spectroscopy, Here we p resent a second version of the sensor, From the first version we deduc ed: i) it is necessary to work at high chopper frequencies to reduce t he effect of 1/f noise, ii) it is necessary to provide a conditioning circuit for each channel, and iii) the conditioning interface must be near the array, Therefore, we propose to amplify and mix the incoming signal to produce a signal at a fixed intermediate frequency (IF), in our case 1 Hz, The fact that the circuit has few components makes poss ible to place 64 conditioners in a small volume (10 x 4.9 x 7.6 cm(3)) using the with SMT technique, The conditioner is divided into eight b oards, Each board has eight channels and an analog multiplexor, These characteristics permit to approach the circuitry to the array, Each ch annel conditioner has up to 100 dB voltage gain, The low IF technique makes it possible to have high-performance circuits with low-cost comp onents.