Coplanar waveguides on AlN for AlGaN/GaN MMIC applications

In this paper we present results on the characterization of Coplanar Waveguides (CPW) on AlN substrates. These transmission lines will be used in matching networks for high power Al- GaN/GaN ampliers. The large currents that will flow inside these ampliers require a large crosssectional conductor area resulting in CPW lines with large signal-to-ground spacings and/or large center conductor widths. The Line-Reflect-Line (LRL) algorithm was used in combination with a capacitance measurement to determine the transmission line parameters. It will be shown that the CPW lines with large dimensions show non-quasi- TEM behavior presumably related to parallel plate modes which influence decreases with sample thickness. The CPW lines show dispersion in the lowfrequency

Advances in silicon phased-array receiver IC's

Phased-Arrays are increasingly used, and require Silicon implementations to result in affordable multi-beam systems. In this paper, CMOS implementations of two novel analogue beamforming multi-channel receivers will be presented. A narrow-band highly linear system exploiting switches and capacitors in advanced CMOS is presented, implementing a fully passive switched capacitor vector modulator exploiting a zero-IF I/Q mixer: This technique is not applicable to very wideband phased-array receivers. These systems require true-time delay beamforming, which is implemented in the second CMOS implementation. An innovative gm-RC implementation of a true-time delay cell is exploited in a four-channel beamforming receiver with more than L.5 GHz bandwidth, in a standard 0.13 um CMOS process. Professional phased-arrays can often not live with the dynamic range limitations imposed by these implementations. To that end a SiGe implementation of an integrated receiver was realized targeting a digital beamforming phased-array. Dynamic range and flexibility of use were the main driving factors. Alltogether, these results show large progress with respect to the feasibility of Silicon-based phased-array front-end implementation for commercial as well as professional phased-arrays. © 2012 IEEE

Theory of asymmetric non-additive binary hard-sphere mixtures

We show that the formal procedure of integrating out the degrees of freedom of the small spheres in a binary hard-sphere mixture works equally well for non-additive as it does for additive mixtures. For highly asymmetric mixtures (small size ratios) the resulting effective Hamiltonian of the one-component fluid of big spheres, which consists of an infinite number of many-body interactions, should be accurately approximated by truncating after the term describing the effective pair interaction. Using a density functional treatment developed originally for additive hard-sphere mixtures we determine the zero, one, and two-body contribution to the effective Hamiltonian. We demonstrate that even small degrees of positive or negative non-additivity have significant effect on the shape of the depletion potential. The second virial coefficient $B_2$, corresponding to the effective pair interaction between two big spheres, is found to be a sensitive measure of the effects of non-additivity. The variation of $B_2$ with the density of the small spheres shows significantly different behavior for additive, slightly positive and slightly negative non-additive mixtures. We discuss the possible repercussions of these results for the phase behavior of binary hard-sphere mixtures and suggest that measurements of $B_2$ might provide a means of determining the degree of non-additivity in real colloidal mixtures

Small sized high-gain PHEMT high-power amplifiers for X-BAND applications

The development of two small sized broadband X-band high-power amplifiers is discussed. The amplifiers are realised with the help of the pseudomorphic HEMT technology of the Fraunhofer Institute for Applied Solid State Physics (FhG-IAF). With the help of this technology the feasibility of integrating a driver and high-power amplifier on a single, small sized, chip is demonstrated. This integration will reduce the number of chips necessary in a Transmit/Receive (T/R) module used in e.g. a phased-array radar antenna. Consequently, the cost of a T/R module is reduced

C-band 10-Watt HBT High-power Amplifier with 50% PAE

The design and measurement of a C-band HBT high-power amplifier (HPA) is discussed. The amplifier is realised in the HB20P power HBT process of UMS. The HPA combines a high average output power of 9 Watt with both a high gain of 21.6 dB and a high power added efficiency (PAE) of 50% over about 20% bandwidth at the nominal 8 V collector voltage. At a collector voltage of 10 V an average output power of 10.3 Watt has been measured. The high PAE is realised with the help of an inverse class F harmonic termination scheme. A good agreement between measurement and simulation results is demonstrated

A novel fast search algorithm for an active load-pull measurement system

In this paper a novel fast search algorithm for an active load-pull algorithm is presented. This algorithm is based on the fact that it is possible to fit, with a minimum number of measurements, the desired parameter, for instance the output power, as function of the load reflection coefficient. The fitted function is used to make a prediction of the location of the optimum load reflection coefficient. Application of the novel load-pull algorithm has resulted in a 8 time reduced measurement time. In this paper also the load-pull measurement system installed at TNO-FEL and some measurement results obtained with the described search algorithm are discussed

A compact broadband high efficient X-Band 9-Watt PHEMT MMIC high-power amplifier for phased array radar applications

In this paper the development and measure­ment results of a compact broadband 9-Watt high-efficient X-band high-power amplifier are discussed. The described amplifier has the following state-of-the-art performance: an average output power of 9 Watt, a gain of 20 dB and an average Power Added Effi­ciency of 35% over a relative bandwidth of 40% at X-band. The amplifier is realised in a pseudomorphic HEMT GaAs MMIC technology developed by the Fraunhofer Institute for Applied Solid State Physics (FhG-IAF) in the scope of the WEAG/TA1/CTP8.1 program

On-chip active gate bias circuit for MMIC amplifier applications with 100% threshold voltage variation compensation

In this paper the design and performance of an on-chip active gate bias circuit for application in MMIC amplifiers, which gives 100% compensation for threshold variation and at the same time is insensitive to supply voltage variations, is discussed. Design equations have been given. In addition, the boundary condition to make the circuit insensitive to supply voltage variations is given. The obtained measurement results demonstrate an excellent agreement with the simulation results. © 2006 EuM