The GBT-SCA, a radiation tolerant ASIC for detector control applications in SLHC experiments

This work describes the architecture of the GigaBit Transceiver – Slow Control Adapter (GBT–SCA) ASIC suitable for the control and monitoring applications of the embedded front-end electronics in the future SLHC experiments. The GBT–SCA is part the GBT chipset currently under development for the SLHC detector upgrades. It is designed for radiation tolerance and it will be fabricated in a commercial 130 nm CMOS technology. The paper discusses the GBT-SCA architecture, the data transfer protocol, the ASIC interfaces, and its integration with the GBT optical link. The GBT–SCA is one the components of the GBT system chipset. It is proposed for the future SLHC experiments and is designed to be configurable matching different front-end system requirements. The GBT-SCA is intended for the slow control and monitoring of the embedded front end electronics and implements a point-to-multi point connection between one GBT optical link ASIC and several front end ASICs. The GBT-SCA connects to a dedicated electrical port on the GBT ASIC that provides 80 Mbps of bidirectional data traffic. If needed, more than one GBT-SCA ASIC can be connected to a GBT ASIC thus increasing the control and monitoring capabilities in the system. The GBT-SCA ASIC features several I/O ports to interface with the embedded front-end ASICs. There are 16 I2C buses, 1 JTAG controller port, 4 8- bit wide parallel-ports, a memory bus controller and an ADC to monitor up to 8 external analog signals. All these ports are accessible from the counting room electronics, via the GBT optical link system. Special design techniques are being employed to protect the operation of the GBT-SCA against radiation induced Single-Event-Upsets to a level that is compatible for the SLHC experiments. The paper will present the overall architecture of the GBTSCA ASIC describing in detail the design of the peripheral controllers for the individual I/O ports, the network controller that implements the connectivity with the GBT ASIC and will discuss the operation modes and the flow of information between the control electronics and the embedded front end ASICs.