A Long-Range Hardware Bubble Corrector Technique for Short-Pulse-Width and Multiple-Registration Encoders

Bubble detection and correction logic is vital in modern data capture devices to solve bubbles in the output thermometer codes due to non-linearities in the scale causing negative bin widths. Previous bubble correction techniques are either unsuitable for short pulse widths and multiple registration (ones-encoder) or have a very short range (all other methods). In this paper, we propose a hardware technique to detect and correct bubbles up to the length of the pulse width while preserving position information using a hybrid between the ones-encoder and a single stage of a modified insertion sort. This design was shown to meet timing on a Xilinx Artix-7 FPGA at 100 MHz or above using only 13% of the device, demonstrating hardware-viability. The design is also fully-pipelined to demonstrate high bandwidths. The limitations of the algorithm are stated and some possible improvements are suggested.