Design of a high accuracy multi-channel analog CMOS Peak Detect and Hold circuits for APD-based PET imaging

This paper represents the design of a high accuracy multi-channel Peak Detect and Hold (PDH) circuits. This PDH measures the energy of an event and is one part of a readout chain for APD (Avalanche Photo Diodes)-based PET (Positron Emission Tomography) imaging. The circuit is designed in a 0.35 μm CMOS process. The PDH proposed is dedicated to ultra low amplitude, large amplitude range (10 mV-1.2 V), and fast peaking time (190 ns) semi-Gaussian pulses. The two-phase technique was used to cancel the major error source of the classical CMOS PDH: offset. A two-gain OTA is applied to decrease the DC error. A 0.7% accuracy for a small input signal (amplitude is less than 200 mV) and a 0.2% accuracy for a large input signal (amplitude is larger than 200 mV) have been obtained from simulation. In our PDH system, the droop rate is negligible.