Dual-Polarity SiPM Readout Electronics Based on 1-bit Sigma-Delta Modulatiom Circuit for PET Detector Applications.

We investigated a simple and effective method to extend 1-bit sigma-delta modulation (SDM) circuit based charge-to-digital converter (QDC) to read dual-polarity silicon photomultiplier (SiPM) output signals. With the same QDC circuit but different voltage biases to the circuit components, the new circuit can read and process both positive and negative polarity signals. We conducted experimental studies to validate its ability to read and process dual-polarity signals and evaluated its performance for Positron Emission Tomography (PET) detector applications. The results, based on energy, coincidence timing and crystal identification measurements, show that the circuit provides equal electronics capability for readout of both polarity signals and good performance for SiPM array-based PET imaging detector applications. Overall, the dual-polarity QDC readout electronics can be easily implemented to extend the range of signal polarity and to provide effective and flexible detector front-end electronics for reading single- or dual-polarity SiPM output signals.