This paper presents an ASIC in 150nm CMOS technology, aiming at Silicon Photomultiplier (SiPM) readout for positron Emission Tomography (PET) application. The chip includes 16 channels, and each is composed of a current buffer, a validation block, a charge sensitive amplifier, a 10-bit ADC and a 12-bit TDC, occupying a size of 2.8×2.2 mm2. An 11.5nC input charge range was designed for a maximum input current of 20mA per channel. The gamma characterization was conducted with 3×3 mm 2 SiPMs (RGB-FBK) coupled to 3×3×5mm 3 LYSO scintillator, showing an energy resolution of 11.2% and Coincident Resolving Timing (CRT) of 663ps. To improve the timing performance, an updated ASIC (32 channels) has been designed and preliminary results show CRT is 433ps with 4×4 mm 2 SiPMs (NUV-HD-FBK) coupled to 3×3×5mm 3 LYSO scintillator.