Abstract An integrated System-on-Chip (SoC) has been designed in 0.6 μ m CMOS mixed analog/digital technology, and tested for high rate alpha particle counting. The sensor is the most innovative part of the chip, with a total active area of 2 × 2.5 mm × 5 mm . The two-stage charge-to-voltage amplification scheme includes a numerical block for offset compensation. Designed with a gain of 700, the chip has been tested in alpha sources: a very high signal over noise ratio was obtained, leading to a detection efficiency of 5 MeV alpha particles close to 100%. The chip is working at room temperature and has been tested up to 300 kHz reset frequency. Future applications of this SoC will focus on detection of fast and thermal neutrons free of gamma contamination.