A Low-Complexity Circuit for On-Sensor Concurrent A/D Conversion and Compression

A low-complexity circuit for on-sensor compression is presented. The proposed circuit achieves complexity savings by combining a single-slope analog-to-digital converter with a Golomb-Rice entropy encoder and by implementing a low-complexity adaptation rule. The adaptation rule monitors the output codewords and minimizes their length by incrementing or decrementing the value of the Golomb-Rice coding parameter k. Its hardware implementation is one order of magnitude lower than existing adaptive algorithms. The compression circuit has been fabricated using a 0.35 muM CMOS technology and occupies an area of 0.0918 . Test measurements confirm the validity of the design.     

An analog-to-digital converter with Golomb-Rice output codes

An analog-to-digital converter with data compression capabilities is described. By sharing circuits between an integrating converter and a Golomb-Rice encoder it is possible to jointly perform the tasks of quantization and coding. The Golomb-Rice codes are generated during the conversion cycle by employing a shift register and a digital multiplexer. The final codeword is read out serially from the shift register. The converter can also work in a noncompressing mode. This design provides a compact circuit suitable for on-sensor compression. Simulations at the system and transistor level corroborate the validity of the design.