Combining BOUNCE and X-ORCA: Improving their real-world utility

Asynchronous time measurement systems, such as tapped delay lines and BOUNCE, consist of a rather large number of independently operating elements, which all have to be calibrated in a rather tedious, preliminary setup process. The required calibration time grows linearly in the number of instantiated elements, which can be as large as thousands of elements in practically relevant systems. Recent research has suggested to seamlessly integrate a second time measurement system, known as X-ORCA, to make the required calibration time constant, i.e., independent of the number of elements. Even though X-ORCA is operating asynchronously as well, it is able to determine the phase shifts between two signals at various on-board locations simultaneously. This paper integrates X-ORCA to calibrate BOUNCE. This hybrid calibration approach improves BOUNCE's precision from 170 ps to 30 ps. This paper describes this approach in detail, and provides the results of intensive tests, which include different FPGAs, temperature changes, and validation by means of external laboratory equipment.