Portfolio of work : Data acquisition & FFT Engine for Optical Coherence Tomography Imaging System
As part of a cost reduction exercise, BBSP engineers produced a short form factor PCI Express card for a very challenging data acquisition requirement. Usually, the sample clock applied to the ADCs is designed to be as stable and jitter free as possible. But a frequency modulated sample clock was one of the key characteristics of the Optical Coherence Tomography (OCT) application the card was designed for. In order to track a modulated laser stimulus, the ADC clock was swept from less than 50MHz to 250MHz in less than 20 microseconds. This required a complete redesign of the ADC clock circuitry, and careful component selection to ensure reliable operation in this unusual configuration. In addition to the custom clocking circuitry, a 2k point FFT engine was instantiated in the Xilinx Virtex 5 FPGA for on board data processing. The customer also required complex application specific trigger logic to properly interface to the system optics unit which provided the frequency modulated laser stimulus. The design underwent complete EMC/EMI testing before delivery.