Design and development of advanced low power hybrid acquisition (ALPHA) ASIC for Antarctic demonstrator for the advanced particle-astrophysics telescope (ADAPT)

Abstract

This document discusses the design, development, and testing results of an ApplicationSpecific Integrated Circuit (ASIC) named ALPHA for the Advanced Particle-astrophysics Telescope (APT) sensor elements readout. ALPHA is responsible for scintillating fiber- trackers, and imaging calorimeters to measure gamma-rays and other cosmic-rays. The readout process includes analog sampling (trackers at 250 MHz and calorimeters at 100 MHz), sample conversion with an Analog to Digital Converter (ADC) of 12 bits resolution, output-data packet transmission, and collection to Field Programmable Gate Arrays (FPGA) operated at 250 MHz. Novel in this architecture is the daisy chaining of the readout, as well as sharing of clocking resources, all to reduce power. When the three ALPHAs were daisy chained with one FPGA, the power consumption per channel was measured at 2.66 mW. For the readout sequence and the data transmission sequence to work adequately, two data paths, two token paths, and two sampling banks are featured. Two paths can bypass any defective ALPHAs, and a token is used for collision avoidance in the data transmission path. The token and data packet transmit in opposite directions from each other. A token starts from the FPGA initially and loops around the daisy chain until the ADAPT ends its mission. On the other hand, the data packets start from each ALPHA. When a token reaches an ALPHA that has a data packet that is waiting to shift out, the data packet starts shifting through the data path toward the FPGA for collection. Two versions of ALPHAs were manufactured by TSMC. The functionality of the digital block was tested for version one ALPHA. After an error of inverted channel select pins in the digital library were corrected, full functionality was tested for version two ALPHA. In conclusion, the ALPHA functions as expected.