Alan Wayne Davis

US Patent:

6822744, Nov 23, 2004

Filed:

May 13, 2002

Appl. No.:

10/144657

Inventors:

Godi Fischer - Narragansett RI
Alan Davis - Fairhaven MA

Assignee:

The Board of Governors for Higher Education, State of Rhode Island and Providence Plantations - Providence RI

International Classification:

G01B 902

US Classification:

356477, 367155, 356450

Abstract:

A modular interferometric imaging system includes a sensor array that senses a physical parameter and provides a plurality of first sensor array output signals indicative thereof. An analog die receives the plurality of first sensor array output signals, and digitizes and modulated each of the first sensor array signals to provide a plurality of digitized signals. A digital die receives the plurality of digitized signals to provide a plurality of received digitized signals, and demodulates the plurality of received digitized signals to provide a plurality of demodulated digitized signals indicative thereof. A processor receives and processes the demodulated digitized signals to provide an imaging system output signal.

US Patent:

59493615, Sep 7, 1999

Filed:

May 12, 1997

Appl. No.:

8/854511

Inventors:

Godi Fischer - Narragansett RI
Alan J. Davis - Fairhaven MA

Assignee:

The United States of America represented by the Secretary of the Navy - Washington DC

International Classification:

H03M 302

US Classification:

341143

Abstract:

A wide-band sigma-delta modulator is disclosed having a cascade of two moators or stages, the first stage being of third or greater order and the second being of second or greater order. Both stages utilize simple ternary quantizers to avoid linearity problems associated with the digital to analog converters in the feedback paths of the modulators and to maintain stable operation. Additional zeros are placed in the noise transfer functions of third or higher order stages by means of additional feedback loops between the output of the third integrator and the second summing junction to maximize the dynamic range. The new topology significantly enhances the dynamic range of the system while hardly affecting the circuit's sensitivity with regard to some non-idealities such as finite amplifier open-loop gains or capacitor ratio mismatches. The excess dynamic range gained by these additional zeros is substantial and independent of OSR, hence, the present invention is particularly useful in wide-band applications where the OSR is inherently low. By employing only two cascaded stages, amplifier gain and capacitor ratio matching requirements are kept reasonably low.