Post-Quantization Dithering with Look-Up Tables

Dithering reduces error correlation and improves spectral purity of quantizers by injecting shaped noise at their input prior to quantization. Despite its ability to improve the Spurious Free Dynamic Range (SFDR) and Total Harmonic Distortion (THD) of quantized signals, dithering can be impractical for implementation in analog-to-digital conversion systems due to its high analog-domain complexity. We propose a method to emulate the effects of dithering exclusively in the digital domain using a Look-Up Table (LUT) architecture, allowing efficient and low-cost performance improvement to existing quantizers through digital post-processing. We present analytical results for how to optimally design the LUT in both the Mean-Square and Maximum-Likelihood sense. When simulated, our proposed technique improves SFDR by 15 dBc and reduces THD by 20 dBc while using less than 1 kB of memory and maintaining the same fixed-point output resolution as the input quantized data.