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A millimeter-wave direct-conversion radio-frequency (RF) transmitter requires precise in-/quadrature-phase (I/Q) mismatch calibration and dc offset cancellation to minimize image rejection ratio (IRR) and LO feedthrough (LOFT) for ensuring satisfactory output spectral purity. We present a 28-GHz CMOS RF transmitter with an improved calibration technique for fifth generation (5G) wireless communication applications. The RF transmitter comprises a baseband amplifier, quadrature up-conversion mixer, power amplifier driver, and quadrature LO generator. The I/Q amplitude mismatch is calibrated by tuning the gate biases of the switching stage FETs of the mixer, the I/Q phase mismatch is calibrated by tuning the varactor capacitances at the LC load of LO buffer, and the dc offset is cancelled by tuning the body voltages of the differential-pair FETs at the baseband amplifier. The proposed technique provides precise calibration accuracy by employing mV-resolution tuning voltage generation via 6-bit voltage digital-to-analog converters. It also covers wide calibration range while minimizing the impact on the circuit's bias point and dissipated current during calibration. Implemented in a 65 nm CMOS process, the RF transmitter integrated circuit shows output-referred 1 dB compression power of +6.5 dBm, saturated output power of +12.6 dBm, and an operating band of 27.5–29.3 GHz while demonstrating satisfactory performances of −55.9 dBc of IRR and −36.8 dBc of LOFT. [ABSTRACT FROM AUTHOR]

In this paper, a reconfigurable multi-mode Class-AB/F power amplifier (PA) is proposed for 0.1–4.2 GHz multistandard applications. The PA operates in linear mode (class-AB) for variable-envelope modulated signals and switching mode (class-F) for constant-envelope modulated signals. The proposed linear mode PA design is suitable for multi-band LTE, IOT, WSN and multi-standard RF transmitter, while switching mode PA design can be used in multi-band IOT-LPWA and BLE (Bluetooth Low Energy) RF transmitter. The proposed PA has a reconfigurable off-chip inter-stage and output matching networks over the specified frequency band, while the input stage is Complementary Current-Reuse common-gate with active shunt feedback configuration to achieve Ultra-Wideband (UWB) input matching. The proposed multi-mode PA is designed using a 130 nm CMOS process. Class-AB PA has a saturated output power of 23.5 dBm ± 1 dB over 0.1–4.2 GHz, a power-added efficiency (PAE) of 41%, a third-order intercept point (OIP3) of 17 dBm, and adjacent channel power ratio (ACPR) of − 29.3 dBc for LTE 15 MHz channel bandwidth. The maximum PAE of 62.1% under the class-F operation is achieved at output power of 24.5 dBm. The PA occupies 0.64 mm2 of chip area, while the estimated off-chip area is 13.3 mm2. The proposed PA consumes 164 mW, and 16 mW in class-AB and class-F, respectively. [ABSTRACT FROM AUTHOR]

Automating the task of high beam switching will significantly reduce glare from oncoming vehicles and thus improving night time driving safety. To avoid temporary blindness and glare from oncoming vehicles, automatic high beam controller is developed. This can be achieved by fixing RF transmitter at starting points of cities. Once a vehicle enters the city, the headlight beam Electronic Control Unit (ECU) in the vehicles receives signal from RF transmitter and the light beam of headlight of the vehicle is automatically switched to a low beam. Once the vehicle leaves the city by crossing RF transmitter the user input is enabled by ECU and the driver can change the beam either high or low manually according to his need. The circuit has been designed and simulated in the Proteus software and accurate switching of the high beam is achieved. This proposed system shows better performance, which will result in safe and glare-free driving at night times. [ABSTRACT FROM AUTHOR]

This paper proposes the use of a triple-line microstrip array for transmitting a magnetic field (|B1+|) into the whole body for magnetic resonance applications at ultra-high field strength, such as 7 T. We explored some technologies that can potentially be applied for whole-body 7 T magnetic resonance imaging, as there is ongoing research on this topic. The triple-line microstrip transmission line (t-MTL) array consists of 32 channels. Each channel has a t-MTL, comprising a main conductor line and two adjacent coupled lines. The adjacent lines are not connected directly to the source. This configuration resulted in increased intensity and a centered |B1+|-field. We compared the proposed structure and some reference radiofrequency (RF) transmitters, such as a patch antenna, using a magnet bore as a waveguide and a whole-body birdcage coil. We evaluated the performance of the t-MTL using cylindrical phantoms. We computed the |B1+|-field from each RF transmitter inside a 3D human model containing more than 200 tissues. We compared their uniformity and field intensity and proposed a t-MTL array that yielded better performance. The proposed design also showed a lower specific absorption rate compared with a patch antenna. [ABSTRACT FROM AUTHOR]

Automating the task of high beam switching will significantly reduce glare from oncoming vehicles and thus improving night time driving safety. To avoid temporary blindness and glare from oncoming vehicles, automatic high beam controller is developed. This can be achieved by fixing RF transmitter at starting points of cities. Once a vehicle enters the city, the headlight beam Electronic Control Unit (ECU) in the vehicles receives signal from RF transmitter and the light beam of headlight of the vehicle is automatically switched to a low beam. Once the vehicle leaves the city by crossing RF transmitter the user input is enabled by ECU and the driver can change the beam either high or low manually according to his need. The circuit has been designed and simulated in the Proteus software and accurate switching of the high beam is achieved. This proposed system shows better performance, which will result in safe and glare-free driving at night times. [ABSTRACT FROM AUTHOR]

This paper presents a television (TV) transmitter for wireless video streaming applications in TV white space band. The TV transmitter is composed of a digital TV (DTV) signal generator and a UHF-band RF transmitter. Compared to a conventional high-IF heterodyne structure, the RF transmitter employs a zero-IF quadrature direct up-conversion architecture to minimize hardware overhead and complexity. The RF transmitter features I/Q mismatch compensation circuitry using 12-bit digital-to-analog converters to significantly improve LO and image suppressions. The DTV signal generator produces an 8-vestigial sideband (VSB) modulated digital baseband signal fully compliant with the Advanced Television System Committee (ATSC) DTV signal specifications. By employing the proposed TV transmitter and a commercial TV receiver, over-the-air, real-time, high-definition video streaming has been successfully demonstrated across all UHF-band TV channels between 14 and 69. This work shows that a portable hand-held TV transmitter can be a useful TVband device for wireless video streaming application in TV white space. [ABSTRACT FROM AUTHOR]

This paper presents a low cost wireless current sensor dedicated to Non-Intrusive Appliance Load Monitoring (NIALM) application. Thanks to the requirement of such technology, two kinds of sensor are studied and realized: one for transient measurement and one for steady-state measurement. Using NIALM algorithms, the transient sensor allows us to determine event detection (On/off operation), while the second one is dedicated to signature analysis and power consumption estimation in order to classify appliances. New design of current sensor, including theoretical analysis and simulation, is presented. The performances of this new Rogowski coil sensor are measured and compared with a commercial product. Finally, a low power transmitter, based on a simple ramp Analog-to-Digital Converter architecture and a PWM-OOK modulation, is proposed and designed in 180 nm CMOS technology. The post-layout simulation exhibits a 1.8 mW power consumption for an output power of −10dBm. [ABSTRACT FROM AUTHOR]

This paper presents a 0.13m CMOS 3-level envelope delta-sigma modulation (EDSM) RF signal generator, which synthesizes a 2.6 GHz-centered fully symmetrical 3-level EDSM signal for high-efficiency power amplifier architectures. It consists of an I-Q phase modulator, a Class B wideband buffer, an up-conversion mixer, a D2S, and a Class AB wideband drive amplifier. To preserve fast phase transition in the 3-state envelope level, the wideband buffer has an RLC load and the driver amplifier uses a second-order BPF as its load to provide enough bandwidth. To achieve an accurate 3-state envelope level in the up-mixer output, the LO bias level is optimized. The I-Q phase modulator adopts a modified quadrature passive mixer topology and mitigates the I-Q crosstalk problem using a 50% duty cycle in LO clocks. The fabricated chip provides an average output power of --1.5 dBm and an error vector magnitude (EVM) of 3.89% for 3GPP LTE 64 QAM input signals with a channel bandwidth of 10/20 MHz, as well as consuming 60 mW for both channels from a 1.2 V/2.5 V supply voltage. [ABSTRACT FROM AUTHOR]