Search

This article presents a quadrature switched/floated capacitor power amplifier (SFCPA) with deep back-off efficiency enhancement. The SFCPA is introduced to decrease the dynamic power consumption at power back-off (PBO), which could improve the system efficiency (SE). The reconfigurable self-coupling canceling transformer (RSCCT) with enhanced tuning range of turn ratio is used to achieve impedance boosting for further improved efficiency at deep PBO. Based on the proposed SFCPA, a watt-level quadrature digital power amplifier (DPA) with IQ cell sharing, hybrid Doherty, and impedance boosting is proposed for deep PBO efficiency enhancement. Implemented in 40-nm CMOS, the proposed DPA with 1.2-/2.4-V supply achieves 30.3-dBm saturated output power ($P_{\mathrm{ out}}$) with 36.6%/32.9%/29.1%/23.7%/18.6%/13.2% SE for 0-/3-/6-/9-/12-/15-dB PBOs at 2.4 GHz. For 60-MHz 256-QAM modulation signal, it delivers 23.32-dBm average output power ($P_{\mathrm{ avg}}$) with an error vector magnitude (EVM) of −31.9 dB and an average drain efficiency (DE) of 30.7%. For 40-MHz 1024-QAM signal, it shows 20.44-dBm $P_{\mathrm{ avg}}$ with an EVM of −35.9 dB and an average DE of 22.6%. [ABSTRACT FROM AUTHOR]

In this article, a wideband quasi-circulator (QC) with the low noise figure (NF) and high 1-dB compression point (P1dB) is proposed. The slotline-based 180° hybrid is introduced to achieve the wideband high transmitter-receiver (TX-RX) isolation. Meanwhile, the bidirectional in-phase stage and the nonreciprocal out-of-phase stage are utilized to obtain specific power-split ratios for the low insertion loss and high antenna-transmitter (ANT-TX) isolation. By using the unequal power split, the proposed QC is without the fundamental 3-dB loss seen in reciprocal ANT interfaces. Besides, to further enhance the TX-RX isolation within a wideband, a reconfigurable inter-stage matching network based on a varactor-tuned capacitor is implemented. To verify the mechanisms mentioned above, a reconfigurable wideband QC operating at 1.75–2.9 GHz is implemented and fabricated. The total power consumption is 224 mW. The measurement exhibits in-band TX-RX isolation of 27–58 dB. The TX-ANT and ANT-RX insertion losses are 4.3–5.0 dB and 1.0–1.9 dB, respectively. The QC also achieves the minimum in-band ANT-RX NF of 3.4 dB. Meanwhile, the measured TX-ANT and ANT-RX IIP3s are 39.4 and 32.5 dBm, respectively. The TX input P1dB is greater than 28.78 dBm, while the RX input P1dB is 23 dBm. The TX-induced ANT-RX P1dB is measured to be 28 dBm. [ABSTRACT FROM AUTHOR]

In this letter, a wideband watt-level digital power amplifier (DPA) with a balance-compensated matching network is proposed for polar transmitters. The balance response of the differential to the single-ended transformer is enhanced by a series-loaded compensation capacitor, which leads to the improvement of the DPA efficiency. To verify the mechanisms, a prototype DPA is fabricated in conventional 40-nm CMOS technology. The proposed DPA operates over 1.2–2.8 GHz and exhibits a peak output power of 32.4 dBm at 2 GHz and a peak drain efficiency of 53.8% at 1.8 GHz. It supports 50-MHz 64-quadratic-amplitude modulation (QAM) with average output power ($P_{\text {avg}}$) of 25.37 dBm, error vector magnitude (EVM) of −26.97 dB, adjacent channel power ratio (ACPR) of −29.61 dBc, and 10-MHz 1024-QAM with $P_{\text {avg}}$ of 22.14 dBm, EVM of −35.75 dB, and ACPR of −35.37 dBc, respectively. [ABSTRACT FROM AUTHOR]

Satisfying the increasing volume of data streaming in modern wireless systems will demand energy-efficient RF front ends with gigabit data rates, high integration levels, and low cost. The power amplifier (PA) is the last door in the RF front end for both the digital and analog kingdoms, one that greatly affects the quality of service of the wireless link [1]. Thus, breaking through barriers (i.e., output power, linearity, efficiency, operation band, and even multifunction) in PA design is of paramount importance right now [2]. Consequently, with the aim of meeting the modern requirements of multistandard wireless applications, such as 5G, narrowband Internet of Things (NB-IoT), wireless local area network (WLAN), and future smart communications, various mixed-signal PAs have been developed and proposed in recent years. [ABSTRACT FROM AUTHOR]

A compact high-resolution reconfigurable phase-tuning line (RPTL) based on self-shielded 3-D interdigital capacitors is presented in this letter. Such a capacitor with high- $Q$ and self-shielded characteristics is used to implement the digitally switchable capacitor array in the RPTL, which is integrated with a coplanar waveguide and can lead to merits of the low loss, high phase-tuning resolution, and compact size. Meanwhile, the grounded shield is utilized in the RPTL to further reduce the loss. To verify the mechanisms of aforementioned structure, a 6-bit digital controlled RPTL is implemented and fabricated using a 40-nm CMOS technology. At 30 GHz, the measured loss of the proposed RPTL is 2.1 dB, while a tuning resolution of 0.38° with an RMS phase error of 0.25° is achieved. [ABSTRACT FROM AUTHOR]

The needs of multiband communication continue to grow, leading to an increase in the number of RF bands. Therefore, to meet system requirements for efficient operation in a compact size, as well as develop multifunction applications, reconfigurable and miniaturized filters using a single signal path are essential. [ABSTRACT FROM PUBLISHER]