In this paper, we present a near-field microwave microscopy method for the characterization of dielectric materials samples in the Industrial, Scientific and Medical (ISM) band. The system proposed is composed of a probe coupled to a dielectric resonator (DR) operating in the TE011 mode. Latter this is used to fix the resonance frequency of the resonator at 2.45 GHz. This system is used for the characterization of dielectric samples with accuracy and high spatial resolution, knowing that they do not have predetermined forms, but a small plane surface.The same device is used for a multi-frequency characterization (4–20 GHz) using resonance frequencies of the cavity instead of one resonance frequency of the DR.

The present paper presents a fully differential 60 GHz four stages low-noise amplifier for wireless applications. The amplifier has been optimized for low-noise, high-gain, and low-power consumption, and implemented in a 90 nm low-power CMOS technology. Matching and common-mode rejection networks have been realized using shielded coplanar transmission lines. The amplifier achieves a peak small-signal gain of 21.3 dB and an average noise figure of 5.4 dB along with power consumption of 30 mW and occupying only 0.38 mm2 pads included. The detailed design procedure and the achieved measurement results are presented in this work.

In this paper, design, manufacture, and measurement of a wideband matching network for a broadband V-shaped square planar monopole antenna (V-SPMA) is presented. Matching network design is unavoidable in most cases even vital to facilitate a maximally flat power transfer gain for an antenna. In the work, a bandpass matching network (BPMN) design is done for a particular square monopole antenna with V-shaped coupling element that has essentially bandwidth increasing effect. Designed BPMN and the antenna forms a VSPMA–BPMN matched antenna structure. “real frequency technique” is employed in the BPMN design. BPMN prototype circuit has been constructed on an FR4 laminate with commercial microwave chip inductors and capacitors. Vector network analyzer gain and reflectance measurements of the matched antenna structure have shown highly compatible results to those of the theoretical design simulations along the passband (~0.8–4.7 GHz). Furthermore, newly proposed distributed capacitor–resistor lossy model for microstrip lines used in the BPMN circuit have exhibited that it can successfully mimic the measured gain and reflectance performance of the matched structure in passband and even in stopband upto 8 GHz. Designed structure can be utilized as a one single wideband broadcasting medium suitable for many communication standards such as GSM, 3G, and Wi-Fi.

In the present paper, we present a dynamic gate biasing technique applied to a 10 W, S-band GaN amplifier. The proposed methodology addresses class-B operation of power amplifiers that offers the potential for high efficiency but requires a careful attention to maintain good linearity performances at large output power back-off. This work proposes a solution to improve the linearity of class-B amplifiers driven by radio frequency-modulated signals having large peak to average power ratios. An important aspect of this work concerns the characterization of the dynamic behavior of GaN devices for gate bias trajectory optimization. For that purpose, the experimental study reported here is based on the use of a time-domain envelope setup. A specific gate bias circuit has been designed and connected to a 10 W – 2.5 GHz GaN amplifier demo board from CREE. Compared to conventional class-B operation with a fixed gate bias, a 10-dB improvement in terms of third-order intermodulation is reached. When applied to the amplification of 16-QAM signals the proposed technique demonstrates significant ACPR reduction of order of 6 dB along with error vector magnitude (EVM) improvements of five points over 8 dB output power back-off with a minor impact on power-added efficiency performances.

This work presents radio-frequency-microelectromechanical-system (RF-MEMS)-based tunable input- and output-matching networks for a multi-band gallium nitride (GaN) power-amplifier applications. In the first part, circuit designs are shown and characterized for a fixed operation mode of the transistor, i.e. either a maximum-output-power- or a maximum-power-added-efficiency (PAE)-mode, which are finally combined into a multi-mode-matching network (M3N); the M3N allows to tune the operation mode of the transistor independently of its operational frequency. The matching networks are designed to provide optimum matching for the power amplifier at three to six different operating frequencies for maximum-output-power- and maximum-PAE-mode. In the frequency range from 3.5 to 8.5 GHz, return losses of 10 dB and higher were measured and insertion losses of 0.5–1.9 dB were demonstrated for the output-matching networks. Further characterizations were performed to test the dependency on the RF-input power, and no changes were observed up to power levels of 34 dBm when cold-switched.

This paper presents the design methodology and the realization of a highly linear and power-efficient reconfigurable dual-band amplifier based on the continuous/Class-ABJ approach. The Class-ABJ theory allows presenting different reactive solutions on both fundamental and second harmonic terminations compared with the standard Class-AB mode. Despite the various terminations, a constant optimum output performance in terms of power, gain, and efficiency can still be achieved. The output impedances are then translated into frequency thus allowing the realization of broadband power amplifiers (PAs) at high-power level of 30 W. In this work, the Class-ABJ broadband approach will be used for the realization of a reconfigurable dual-band power amplifier operating in the two frequency bands 2.1–2.2 and 2.5–2.6 GHz. Continuous wave (CW) measurements on the realized PA show power and efficiency greater than 17 W and 55% in the two frequency bands with peak values up to 30 W and 63.7%. Indeed, it is shown that such novel modes can be predistorted and therefore the linearity requirement can also be met.

Two compact H-band (220–325 GHz) low-noise millimeter-wave monolithic integrated circuit (MMIC) amplifiers have been developed, based on a grounded coplanar waveguide (GCPW) technology utilizing 50 and 35 nm metamorphic high electron mobility transistors (mHEMTs). For low-loss packaging of the circuits, a set of waveguide-to-microstrip transitions has been realized on 50-μm-thick GaAs substrates demonstrating an insertion loss of <0.5 dB at 243 GHz. By applying the 50 nm gate-length process, a four-stage cascode amplifier module achieved a small-signal gain of 30.6 dB at 243 GHz and more than 28 dB in the bandwidth from 218 to 280 GHz. A second amplifier module, based on the 35-nm mHEMT technology, demonstrated a considerably improved gain of 34.6 dB at 243 GHz and more than 32 dB between 210 and 280 GHz. At the operating frequency, the two broadband low-noise amplifier modules achieved a room temperature noise figure of 5.6 dB (50 nm) and 5.0 dB (35 nm), respectively.

We present a technique allowing the stabilization and tuning of a modulation sideband in the presence of high-carrier frequency jitter and increased carrier phase noise. This technique is of particular interest in communication systems where oscillators providing the carrier signal cannot be stabilized by a conventional phase-locked loop, such as systems relying on low-cost optical LO generation techniques. The results obtained in simulation are validated by measurements carried out on a modular system demonstrator.

The paper presents millimeter-wave (mm-wave) signal sources using a hetero-integrated InP-on-BiCMOS semiconductor technology. Mm-wave signal sources feature fundamental frequency voltage-controlled oscillators (VCOs) in BiCMOS, which drive frequency multiplier–amplifier chains in transferred-substrate (TS) InP-DHBT technology, heterogeneously integrated on top of the BiCMOS wafer in a wafer-level bonding process. Both circuits are biased through a single set of bias pads and compact low-loss transitions from BiCMOS to InP circuits and vice versa have been developed, which allows seamless signal routing through both technologies exhibiting 0.5 dB insertion loss up to 200 GHz. One VCO operates at 82 GHz with a tuning range of 600 MHz and an output power of approximately 8 dBm. A frequency doubler combined with this VCO circuit delivers 0 dBm at 164 GHz and a frequency tripler with a similar VCO delivers −10 dBm at 246 GHz. Another hetero-integrated W-band doubler–amplifier circuit demonstrates 12.9 dBm saturated output power with 5.9 dB conversion gain at 96 GHz. A direct comparison of the TS InP-DHBT MMIC with either silicon or traditional AlN carrier substrates shows the favorable properties of the hetero-integrated process discussed here. The results demonstrate the feasibility of hetero-integrated circuits operating well above 100 GHz.

This paper presents power results of L-band packaged hybrid amplifiers using InAlN/GaN/SiC HEMT power dies. The high-power densities achieved both in pulsed and continuous wave (cw) modes confirm the interest of such technology for high-frequency, high-power, and high-temperature operation. We present here record RF power measurements for different versions of amplifiers. Up to 260 W, i.e. 3.6 W/mm, in pulsed (10 µs/10%) conditions, and 105 W, i.e. 2.9 W/mm, in cw conditions were achieved. Such results are made possible thanks to the impressive performances of InAlN/GaN transistors, even when operating at high temperatures. Unit cell transistors deliver output powers of 4.3 W/mm at Vds = 40 V in the cw mode of operation at the frequency of 2 GHz. The transistor process is described here, as well as the amplifiers design and measurements, with a particular focus to the thermal management aspects.

In this paper, we report a new high-speed and high-power switching circuit based on GaN HEMT's. The elementary switching cell, composed of two GaN HEMT's and two resistors, acts like a power threshold comparator with high-output voltage. Theoretical analysis of static and dynamic circuit operation points out the dependence of efficiency and switching speed to the main circuit elements. Four switching cells are then combined together thanks to SiC Schottky diodes to design a multi-level power switch that can be used as a power supply modulator for envelope tracking power amplifiers. The designed four-level supply modulator, based on Nitronex GaN HEMT's, exhibits more than 75% of efficiency for an envelope signal up to 4 MHz, a switching frequency of 20 MHz and output voltages in the range of 12–30 V.

In this paper, we present the first ridge-gap waveguide resonator made with a polymer base. It is designed for the frequency range 220–325 GHz, and is fabricated solely using a Au coated two-layer SU8-based process. The design is based on previous work done with Si. The new process has advantages such as fewer and cheaper process steps. The SU8 ridge-gap waveguide resonator is made in order to obtain attenuation characteristics via the measured Q-factor of the resonator. The ridge-gap waveguide resonator has the same dimensions as the previous one fabricated in Si, and the same thickness of the Au coating. The SU8-based resonator shows an attenuation loss of 0.41 dB/mm at 282.2 GHz compared to the Si-based resonator with an attenuation loss of 0.043 dB/mm at 283.5 GHz. This makes the SU8 process a more cost-effective alternative to the Si process

In this paper, a passive double-balanced mixer in SiGe HBT technology is presented. Owing to lack of suitable passive mixing elements in the technology, the mixing elements are formed by diode-connected HBTs. The mixer uses lumped element Marchand baluns on both the local oscillator (LO) and the radio frequency (RF) port. A break out of the Marchand balun is measured. This demonstrates good phase and magnitude match of 0.7° and 0.11 dB, respectively. The Marchand baluns are broadband with a measured 3 dB bandwidth of 6.4 GHz, while still having a magnitude imbalance better than 0.4 dB and a phase imbalance better than 5°. Unfortunately with a rather high loss of 2.5 dB, mainly due to the low Q-factor of the inductors used. The mixer is optimized for use in doppler radars and is highly linear with a 1 dB compression point above 12 dBm IIP2 of 66 dBm. The conversion gain at the center frequency of 8.5 GHz is −9.8 dB at an LO drive level of 15 dBm. The whole mixer is very broadband with 3 dB bandwidth from 7 to 12 GHz covering the entire X-band. The LO–IF, RF–IF, and RF–LO isolation is better than 46, 36, and 36 dB, respectively, in the entire band of operation.

Directional modulation (DM) is a recently introduced technique for secure wireless transmission using direct physical layer wave-front manipulation. This paper provides a bit error rate (BER)-based DM array synthesis method. It is shown for the first time that the standard constellation mappings in In-phase and Quadrature (IQ) space to a pre-specified BER can be exactly achieved along a given specified spatial direction. Different receiver capabilities are investigated and different assessment metrics for each case are discussed. The approach is validated for a 1 × 4 element dipole array operating at 1 GHz.

This work presents a wideband amplifier, in 12–19 GHz frequency range, with noise figure lower than 1.35 and 26 dB of gain developed in the frame of European Component Initiative program, supported by European Space Agency. By using a flexible biasing, this amplifier allows us to reach a significant linearity, output power at 1 dB compression up to 19 dBm, or to reduce the DC consumption close to 210 mW. This versatility implies that a user has a low-noise amplifier) or medium power amplifier in a single chip. The D01PHS process, from OMMIC foundry, has been chosen in order to realize this MMIC, thanks to linearity capability, and also thanks to a significant potential for low-noise amplification.

In this paper, a low-power CMOS LC voltage-controlled oscillator (VCO) with body-biasing and low-phase noise with Q-enhancement techniques is presented. A self-body biased circuit is introduced that can reduce power consumption. Some derivations of the Q-enhancement and how to improve the phase noise of the circuit are also discussed. This chip is implemented by the Taiwan Semiconductor Manufacture Company 0.18 µm 1P6M process. The measurement results exhibit a tuning range of 14.7% from 4.92 to 5.7 GHz at a supply voltage of 1.4 V. The power consumption of the core circuit and figure of merit are 2.5 mW and −188.6 dBc/Hz. The phase noise is −118 dBc/Hz@1 MHz at an operation frequency of 4.94 GHz.

This paper presents a new concept for the fine tuning of high-Q bandpass filters to compensate for small response deviations due to manufacturing tolerances and temperature variations. Discrete frequency tuning steps are obtained using a rectangular waveguide resonator loaded with a reconfigurable E-plane circuit. Ohmic micro electromechanical systems (MEMS) switches can be placed along thin E-plane metal strips so as to modify the E-field distribution of the TE101 resonant mode, thus the central frequency of the filter. As an example, 0.1% frequency steps can easily be obtained in a 10 GHz resonant cavity. The use of low-loss substrates ensures high-quality factors of the order of 1000. The feasibility of the proposed approach is demonstrated both by full-wave simulations and by fabricating and measuring an X-band hardwired prototype.