High-Speed ADC for Nuclear Physics Experiments

Several nuclear physics experiments require accurate timing measurements and transient digitization at high sampling rates, exceeding 1 gigasamples per second (GSPS). To date, only few transient digitizer chips have been developed for this purpose and they are based on storing the analog samples onto long buffers from which they are digitized with low-rate analog-to-digital converters (ADC). These digitizers provide low power dissipation per channel, but they suffer from limited buffer length, long latency between samples (microseconds) and high jitter (> few picoseconds). A low-power, low-jitter, continuously sampling ADC would be a solution to the problems described above, but the available ADCs have too high-power dissipation (>2.5W) to be used in most of the experiments. In this SBIR program Alphacore, Inc. will develop an ADC that has the following specifications: (1) Sampling rate of 10GSPS; (2) Jitter 5GHz; (5) ENOB > 10.0 (calculated for the full first Nyquist zone and includes jitter); (6) Power consumption: 1Mrad(Si). In Phase I Alphacore will design and simulate all the sub-circuits needed in the ADC. Alphacore aims to demonstrate the feasibility of the concept during Phase I, followed by fabrication and testing of a prototype in Phase II. Jefferson Lab has several needs for this type of ADC in their nuclear physics experiments, as expressed in their support letter included in the submission package. Another application is the planned Electron-Ion Collider. In addition, Lightsource II, a new facility at Brookhaven National Laboratories providing an extremely high brightness x-ray source for basic energy science studies and requiring a rad-hard, gigasample digitizer that does not have any deadtime. Alphacore’s digitizer can also benefit many other applications, such as radio astronomy applications, radar and LIDAR applications, communications applications and high-speed test equipment.