Photonic A/D Converters for Wideband and High-Dynamic-Range Performance
Abstract
Navy TBMD AEGIS ships will be required to perform radar tracking and exoatmospheric discrimination against future TBM threats that will have significantly greater range, higher velocity, and lower radar cross section than the current predominate threat. A significant contributor to current radar tracking and discrimination limitations is the downconversion chain to intermediate frequency (IF) and the analog-to-digital (AID) conversion. Conventional multistage downconversion receivers are limited in dynamic range, linearity, and A/D conversion rate. Performing the A/D conversion at RF rather than IF can provide a solution to these limitations as well as a significant increase in radar sensitivity. Technology development for photonic A/D converters could lead to a new generation of receivers with superior linear dynamic range and sensitivity to counter the future TBM threat. This paper presents a novel approach to A/D conversion based upon precise optical sampling and optical phase discrimination, with the proposed development of a low jitter mode-locked laser (<50 fs), and the development of charge-based quantizers with greater than 14 bit linearity (at 6 gigasamples per second). Initial measurements will be presented for UHF and S-band architectures supporting the extension of A/D converter performance well beyond the commercial regime. Converters based on this technology would enable a new class of digital receivers with about 12 dB improvement in signal-to-noise ratio, a 90 dB spurious-free dynamic range, and a 100-fold improvement in instantaneous bandwidth over conventional receiver approaches.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1998
- Accession Number
- ADA355857
Entities
People
- C. E. Dickerson
- J. C. Twichell
- Z. J. Lemnios
Organizations
- Massachusetts Institute of Technology