Performance analysis of phoswich/APD detectors and low noise CMOS preamplifiers for high resolution PET systems

An integrated, 0.8-μ CMOS charge-sensitive preamplifier previously designed for LSO/APD based PET systems has been further investigated for use with multi-crystal/APD PET detectors. In addition to low-noise, wide-band performance and power efficiency, high dynamic range and good signal-to-noise ratio over a broad range of shaping times are required to process the signals from crystals being used in phoswich detectors, which have a wide range of scintillation decay time and light output characteristics. The preamplifier equivalent noise charge (N_eq) was measured as a function of input capacitance and amplifier shaping time constant. The performance of the preamplifier was also assessed using APDs coupled to a variety of scintillators. Measurements were obtained at a preamplifier input-device current of 2 and 4 mA. The higher bias lead to marginal improvements of the timing performance but had no effect on energy resolution