Front-end Electronics for Spectroscopy Applications (FESA) IC

Non-destructive evaluation and inspection using X-rays require the detection of large photon fluxes. Typically, this requirement is met by operating the detectors in current mode, at the expense of the ability to measure the photon energy. This makes it necessary to obtain the energy information by other means, such as varying the energy of the X-ray source. We have developed an integrated circuit for the fast readout of solid-state X-ray and gamma ray detectors with multi-energy capability. The 32-channel Front-end Electronics for Spectroscopy Applications (FESA) chip is designed to handle photon rates in excess of one million photons per second per channel. In each channel, the detector pulses are shaped and amplified and then processed by a simple pulse-height analyzer that consists of five comparators each of which is connected to a dedicated counter. The 160 counters an each chip can be read out in less than 25 μs. The FESA IC features digitally controlled gains and offsets, a calibration input and an analog test output, both of which can be connected to any channel. The five comparator threshold voltages, common to all channels, are provided externally, as is the current that controls the pulse shaping time