The architecture of a multi-channel front-end system is important for realizing a high-resolution PET system. We propose a novel front-end readout electronic system with TDC to deal with time information for PET system which can easily design the timing control. Each channel consists of a charge preamplifier, slow/fast shaper, discriminator and a analog memory. There are a ADC and a TDC to process the energy information and time information for each channel at the same time. In this paper, the whole system signals flow is all simulated by MATLAB. The simulation results show that the proposed system can process slender current from the detector and achieve the energy and time information. The proposed architecture can be applied to high-resolution PET imaging systems with multi-channel ASICs.

This paper presents a high-resolution multi-channel Time-to-Digital Converter (TDC) for Positron Emission Tomography (PET) imaging system. The TDC using a two-level conversion scheme is proposed for obtaining high timing resolution. Double 10-bit gray counters are designed for coarse conversion while a multiphase sampling technology is presented for fine conversion. In order to achieve better timing resolution with either a faster technology, an array of Delay-locked loops is chosen as a timing generator. A prototype chip of 3-channel TDC is designed and fabricated in AMS 0.35µm CMOS technology. The area of the chip is 8.4 mm 2 in size. The measured range of the TDC is 10µs. The time tap is reduced to 71ps with a reference clock of 100MHz. The differential nonlinearity is ±0.1LSB. The circuits will be extended to 64 channels for small animal PET imaging systems.