Digital phase tightening for improved spatial resolution in millimeter-wave imaging systems

Imaging systems using millimeter-wave frequencies allow for the possibilities of vehicular radar and concealed weapons detection. By using silicon technology, the integration of millimeter-wave circuits can reach new levels that were previously impossible. This thesis discusses the challenge and design of a mm-wave imaging system using a technique called digital phase tightening for improved spatial resolution. Digital phase tightening uses feedback and oversampling to accurately measure the amplitude and phase of an incoming signal. Furthermore, it can be implemented using only a delay-lock loop, an analog-to-digital converter, and a counter. A proof of concept system utilizing a 2.4GHz delay-lock loop with supporting circuitry is designed in 90nm CMOS. Test results demonstrate a proof of concept system with a measured DLL resolution of 41.7ps that consumes 36mW of power. The goal of the system is to reduce the jitter of phase measurements to the order of femto-seconds. In the proto system, the quantization error is larger than the Gaussian noise; therefore, significant improvements in the accuracy of the phase measurements were not observed.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Lu, Ke, S.M. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• Charles G. Sodini.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/47817

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/47817