1,720,964 research outputs found
A current re-use PA-VCO cell for low-power BLE transmitters
No full textA current re-use PA-VCO cell for FSK transmitters is presented. High efficiency and low phase noise are obtained through the stacking of a PA and a class-C VCO. Without the use of any DC-DC converters, the voltage headroom of these two blocks can be set maximizing the efficiency of both the PA and the VCO. The structure is inserted in a 130nm CMOS BLE transmitter. A TX efficiency of 17.5% is achieved delivering an output power of -1dBm at 2.4GHz with a VCO phase noise of -129dBc/Hz @ 2.5MHz frequency offset
Class-C PA-VCO Cell for FSK and GFSK Transmitters
No full textIn this paper, a Class-C PA-VCO cell tailored to FSK/GFSK transmitters is presented. In the proposed solution, a Class-C VCO and a common-gate stage PA are stacked in a current-reuse architecture operating with 1.2 V power supply. The PA and the VCO efficiencies are maximized by adjusting their voltage headroom without the use of any DC-DC converters. The PA-VCO is inserted in a transmitter based on an open-loop architecture. The presented prototype, fabricated in 0.13 μm CMOS technology, occupies an active area of 0.2 mm2. A maximum TX efficiency of 17.5% is achieved while the TX is delivering an output power of -1 dBm at 2.45 GHz. A phase noise of -129 dBc/Hz at 2.5 MHz frequency offset results in a carrier-frequency drift below 7 Hz/s and an FSK error below 0.7%, which allows the transmitter to operate in open-loop while delivering long data-packets. The transmitter is also compliant to BLE specifications when FSK and GFSK modulations with index of 0.5 are applied
A low-power sub-GHz RF receiver front-end with enhanced blocker tolerance
No full textThis paper presents a class-AB sub-GHz RF receiver front-end suitable for ultra-low power application. By exploiting transistors' class-AB operation in both the RF and baseband sections, the receiver front-end achieves a very low sensitivity and an elevated blocker tolerance while keeping a low power consumption. Such performance makes the receiver suitable for both short-range (e.g. 802.15.4) and long-range (e.g. LoRa) applications. The proposed RF front-end has been implemented in 0.13um CMOS technology, operates in the 868/915MHz ISM bands, and exhibits an in-band gain of 50dB, noise figure of 2.7dB, out-of-band HP3 of +2dBm, out-of-band IIP2 of +37dBm, out-of-band P1dB of -10.5dBm, while draining 2.1mA from a 1.2 V supply
A 2.4-GHz 1.3-mW OQPSK RF Front-End TX Based on an Injection-Locked Power Amplifier
No full textAn injection locking power amplifier is presented. The proposed solution, tailored to quadrature phase shift keying (QPSK) modulation for IoT has been realized by exploiting the property of an injection-locked frequency divider to work as a phase rotator. Hence, the divider's output is directly coupled to the antenna by a transformer to deliver the desired output power. The combination of these two ideas resulted in a high-efficiency, high-bandwidth QPSK RF front-end for IoT, capable of operating at up to 120 Mbit/s and delivering 1.3-mW output power while burning 3.4 mW
A 6.7-to-9.2GHz 55nm CMOS hybrid Class-B/Class-C cellular TX VCO
No full textThe design of very-wide-band CMOS voltage-controlled oscillators (VCOs) compliant with the phase-noise specifications of cellular transmitters is non-trivial, especially considering the GSM standard, where the phase noise exhibited by the local oscillator (LO, generated by the cascade of VCO, buffers, and usually frequency dividers) should be several dB below -162dBc/Hz at 20MHz frequency offset from the carrier. As shown in [1], challenging phase-noise requirements can embrace the WCDMA transmitter as well (e.g. -166dBc/Hz at 45MHz frequency offset for WCDMA band VIII), if cheap antenna duplexers are chosen to minimize costs. In such scenarios, and particularly in the very relevant case of WCDMA transmitting at moderate power levels, the LO power efficiency is still one of the limiting factors for a long-lasting battery life, motivating the ongoing quest for VCO power optimization. © 2012 IEEE
#x03BC;m CMOS technology
No full textOne of the main goals for the next generation of radios for wireless sensor and body-area networks (WSN and WBAN) is a sub-mW receiver (RX) compliant with energy-harvested supplies. In this direction, the Bluetooth standard has introduced a low-energy operative mode (BLE) with wider channel spacing (2MHz) and relaxed blocker tolerance. The minimum sensitivity required is -70dBm but even with a sensitivity 10dB lower the BLE receiver can have a noise figure close to 19dB [1]. Although linearity and noise specs have been significantly relaxed, the design of a sub-mW solution remains challenging since the power dissipation cannot be simply scaled with the spurious-free-dynamic-range (SFDR). In fact, the ultimate bound is set by the power burned in the voltage-controlled oscillator (VCO), which is used for the generation of the local oscillator (LO) necessary for the signal downconversion. Since, for a targeted phase noise, the current required by the VCO is inversely proportional to the quality factor of the resonator adopted, a straightforward approach is to use a high-Q tank like the FBAR used by Wang et al. [2]. However in low-cost CMOS processes, when high-Q resonators are not present, an alternative strategy is to share the VCO bias current with the other blocks of the RF front-end as in the LMV cell proposed by Tedeschi et al. [3]
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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