A filtering unit is presented. The filtering unit includes at least two operational amplifiers, where each of the at least two operational amplifiers includes an input end and an output end, where the input end of one operational amplifier is coupled across the corresponding input end of another operational amplifier of the at least two operational amplifiers. The filtering unit also includes a direct current link operatively coupled to the at least two operational amplifiers and at least one thermoelectric module, where each thermoelectric module includes a conducting layer, where the direct current link and at least one of the at least two operational amplifiers are operatively coupled to the at least one thermoelectric module. A filtering system is also presented.