Accession Number:

ADA355857

Title:

Photonic A/D Converters for Wideband and High-Dynamic-Range Performance

Descriptive Note:

Corporate Author:

MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB

Report Date:

1998-01-01

Pagination or Media Count:

8.0

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 AD conversion rate. Performing the AD 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 AD 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 AD 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 AD 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.

Subject Categories:

  • Active and Passive Radar Detection and Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE