Modularized pipeline readout electronics for SuperKEKB

To explore a new physics in the flavor sector, we plan the SuperKEKB upgrade with a luminosity of 5times10³⁵ cm^-2s^-1. To cope with the higher trigger rate up to 30 kHz, and the severe background condition, we develop a new pipelined data acquisition system. The new readout system is designed as a composite of a sub-detector specific part customized to meet the requirements of each sub-detector and a common readout platform part, in order to reduce costs for maintenance and development. The sub-detector specific part should have a signal digitizer synchronized with 42.3 MHz reduced RF clock, a level-1 pipeline buffer to hold data for trigger delay time of 3-5 mus, and a communication logic to the trigger system in a fixed protocol. These functions are implemented on a 76times186 mm² sized module. A 17-bit TDC module that handles 24 channels in parallel has been developed for the drift chamber readout of SuperBelle in a low luminosity stage. A readout system test with TDC emulator modules mounted on the common platform shows that the new readout system works at a more than 30 kHz input trigger rate.