Design and performance of 0.18-μm CMOS charge preamplifiers for APD-based PET scanners

The CMOS 0.18-μm technology was investigated for two analog front-end projects: the low power budget rat-head mounted miniature Rat Concious Animal PET (RatCAP) scanner, and the high performance, low-noise, high-rate PET/CT application. The first VLSI prototypes consisted of 1 mW and 5 mW charge sensitive preamplifiers (CSP) based on a modified cascode telescopic architecture. Preliminary experimental results were consistent with simulated data obtained and confirmed the model parameters for subsequent fabrications. Better noise characteristics were achieved with the high-performance device powered at 5 mW. Time resolutions of 2.49 ns and 1.56 ns (FWHM) were achieved by the 1-mW and 5-mW CSPs, respectively. Both CSPs achieve a similar energy resolution, which is mainly determined by the scintillator/APD-based detector. Preliminary results indicate that the CMOS 0.18-μm technology is suitable for both the low-power and the high-performance PET front-end applications, and that room for improvement is available.