A 9-decade current to frequency converter with active leakage compensation

An Application Specific Integrated Circuit (ASIC) that is able to digitize input current starting from a few femtoamperes (fA) up to microamperes (μA), was designed for the environmental monitoring of the background radiation and for radiation protection at CERN. The Ultra-low Picoammeter 2 (Utopia 2) ASIC, is based on the current to frequency converter (CFC) architecture and can compensate for the net input leakage currents due to a dummy channel scheme. The replica leakage current can follow the temperature variations and provide a leakage current-free readout front-end for radiation detectors