Browsing by Author "Bertrand, Kaoutar"

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All-Digital LTE SAW-Less Transmitter With DSP-Based Programming of RX-Band Noise
(2017-11-21) Roverato, Enrico; Kosunen, Marko; Cornelissens, Koen; Vatti, Sofia; Stynen, Paul; Bertrand, Kaoutar; Korhonen, Teuvo; Samsom, Hans; Vandenameele, Patrick; Ryynanen, Jussi
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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 mmsuperscript2. 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.
All-digital RF transmitter in 28nm CMOS with programmable RX-band noise shaping
(2017-03-02) Roverato, Enrico; Kosunen, Marko; Cornelissens, Koen; Vatti, Sofia; Stynen, Paul; Bertrand, Kaoutar; Korhonen, Teuvo; Samsom, Hans; Vandenameele, Patrick; Ryynänen, Jussi
A4 Artikkeli konferenssijulkaisussa
The crowded radio spectrum allocated for 3G/4G mobile communication, together with the growing demand for higher data-rates, has led to the situation where transceivers need to support FDD operation in multiple frequency bands with different TX-RX duplex spacing. In order to reduce costs and enable SAW-less operation, many recent transmitter implementations have thus targeted stringent out-of-band (OOB) emission levels. Analog-intensive TX architectures achieve low OOB noise at the price of large area consumption, as complex reconstruction filters are used to suppress DAC quantization noise and image replicas [1,2]. On the other hand, due to the lack of analog filtering, digital-intensive TX architectures need 12-14b DAC resolution for low OOB noise, which complicates DAC design and typically requires DPD or calibration [3-5]. This work presents an RF transmitter implementing a fully digital solution to the aforementioned challenge. Instead of using bulky analog filtering or high resolution DAC, the disclosed TX employs digital ΔΣ modulation and mismatch shaping to attenuate the DAC noise at a programmable duplex distance. This solution enables -160dBc/Hz noise in the RX-band, by using only a 10b DAC without DPD, calibration or analog filtering.