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All-Digital LTE SAW-Less Transmitter With DSP-Based Programming of RX-Band Noise | IEEE Journals & Magazine | IEEE Xplore

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


Abstract:

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...Show More

Abstract:

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 mm2. 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.
Published in: IEEE Journal of Solid-State Circuits ( Volume: 52, Issue: 12, December 2017)
Page(s): 3434 - 3445
Date of Publication: 09 November 2017

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