Optical Oversampled Analog-to-Digital Conversion
Abstract
A new approach to optical analog-to-digital (A/D) conversion based on oversampling and error diffusion coding techniques is proposed. This new approach combines the high resolution capabilities of classical oversampled A/D conversion with the high speed of optical processing technology to extend the resolution and conversion rates beyond those currently possible with other electronic or optical converters. The optical approach is device independent, requiring only optical thresholding, subtraction, and digital logic for implementation. The underlying concept is to trade bandwidth for improved amplitude resolution using advanced signal processing techniques. This new approach to optical A/D conversion differs from classical Nyquist rate optical A/D conversion in that each signal sample is not necessarily quantized to the closest reconstruction level. The analog input signal is first optically sampled at a frequency much greater than the Nyquist frequency and is then quantized by a modulator which incorporates one-bit quantizers and linear filters in a negative feedback architecture for the purpose of reducing the quantization noise within the signal baseband. This in-band noise reduction is accomplished by spectrally shaping the quantization noise, forcing most of the noise power to frequencies above the signal's cutoff frequency.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 29, 1992
- Accession Number
- ADA252695
Entities
People
- Barry L. Shoop
Organizations
- Stanford University