All-Digital LTE SAW-Less Transmitter With DSP-Based Programming of RX-Band Noise

We present the first all-digital LTE transmitter (TX) using programmable digital attenuation of receive band (RX-band) noise. The system is architectured to fully exploit the speed and low cost of DSP logic in deep-submicrometer CMOS processes, without increasing at all the design effort of the RF c...

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Bibliographic Details
Published in:IEEE journal of solid-state circuits 2017-12, Vol.52 (12), p.3434-3445
Main Authors: Roverato, Enrico, Kosunen, Marko, Cornelissens, Koen, Vatti, Sofia, Stynen, Paul, Bertrand, Kaoutar, Korhonen, Teuvo, Samsom, Hans, Vandenameele, Patrick, Ryynanen, Jussi
Format: Article
Language:English
Subjects:
Acoustic noise
All-digital transmitter (TX)
Attenuation
Bandpass filters
Baseband
Circuits
CMOS
Delta-sigma modulation
delta–sigma
Design standards
Linearity
Low cost
LTE
mismatch-shaping
Noise
Noise measurement
Noise shaping
Quantization (signal)
Radio frequency
receive band (RX-band) noise
RF-DAC
Surface acoustic waves
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Summary:We present the first all-digital LTE transmitter (TX) using programmable digital attenuation of receive band (RX-band) noise. The system is architectured to fully exploit the speed and low cost of DSP logic in deep-submicrometer CMOS processes, without increasing at all the design effort of the RF circuitry. To achieve operation without surface acoustic wave filter, the TX uses digital bandpass delta-sigma modulation and mismatch-shaping to attenuate the DAC noise at a programmable duplex distance. These functions can be implemented entirely within DSP, thus taking advantage of the standard digital design methodology. Furthermore, the fully digital RX-band noise shaping significantly relaxes the performance requirements on the RF front-end. Therefore, 10 bits of resolution for the D/A conversion are sufficient to achieve -160 dBc/Hz out-of-band (OOB) noise, without need for digital predistortion, calibration, or bulky analog filters. The TX was fabricated in 28-nm CMOS, and occupies only 0.82 mm 2 . Besides low OOB noise, our system also demonstrates state-of-art linearity performance, with measured CIM3/CIM5 below -67 dBc, and adjacent-channel leakage ratio of -61 dBc with LTE20 carrier. The circuit consumes 150 mW from 0.9-/1.5-V supplies at +3 dBm output power.
ISSN:0018-9200
1558-173X
DOI:10.1109/JSSC.2017.2761781