Abstract For the readout of the upgraded inner tracker of the BESIII experiment based on a innovative lightweight Cylindrical Gas Electron Multiplier technology a custom readout electronics is being developed. The special feature of this new front-end is the ability to perform an analog charge measurement in parallel to the event time stamp, operating in a constrained power envelop within a superconductive solenoid. The core of the new front-end is a custom designed 64ch ASIC featuring a fully digital output and operated in triggerless mode. Sustained rate per channel is up to 60 kHz. The TDCs time resolution is better than 100 ps. The energy measurement can be obtained from a time-over-threshold (ToT) measurement or by a 10-bit digitization of the peak amplitude by a sample and hold circuit (S/H).