Delta-Sigma digital-RF modulation for high data rate transmitters

A low power, wideband wireless transmitter utilizing [Delta]-[Sigma] direct digital modulation of an RF carrier is presented. The transmitter architecture replaces high dynamic range analog circuits with high speed digital circuits and a passive LC bandpass filter, saving power and area compared to conventional IQ modulators for wideband systems. A prototype transmitter IC built in 0.13 pm CMOS demonstrates a data rate of 1.2 Gb/s using OFDM modulation in a bandwidth of 200 MHz centered at 5.25 GHz. The modulator consumes 187 mW and occupies a die area of 0.72 mm2. A quadrature digital-IF approach eliminates modulator LO feedthrough and image spurs from the output spectrum without requiring analog circuitry or system calibration, simplifying the design of the transmitter. The largest modulator spur is measured to be -47 dBc. Measured SNDR over a 200 MHz bandwidth is 43 dB. Successful implementation of the [Delta]-[Sigma] RF modulator requires the design of a high-Q, tunable RF bandpass filter, and a low power, high speed digital [Delta]-[Sigma] modulator. A 4th order passive LC bandpass filter with center frequency of 5.25 GHz is designed and implemented using differential coupled resonators.

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

2007

Author dc:creator

• Jerng, Albert

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/1721.1/38675

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/38675