J. Costa Freire

Low cost LTCC filters for a 30GHz satellite system

This paper deals with the improvement on low cost LTCC technology to achieve the specifications of planar filters for a 30GHz Satellite system transmitter. Test structures were fabricated on low cost LTCC technology, presently available for lower frequencies, to characterise its performances up to 40GHz. From this study, guidelines for the design of 30GHz circuits were obtained. Based on these results and their constraints, several solutions for a 30GHz transmitter filter were designed. A comparison between the LTCC filters with active and passive alternative solutions implemented on GaAs monolithic technology is also presented. The feasibility of millimeterwave filters on LTCC with a reasonable yield for mass production is demonstrated.

Monolithic mixers with MESFETs technology to up and down convert between C and V band

In this paper the design of singly balanced mixers to convert C to V hand signals are presented. A step by step design technique is described, based on harmonic balance simulations. The mixer devices are Schottky diodes compatible with a GaAs MESFET technology. The mixer was optimised for minimum conversion losses on the widest possible bandwidth when used as an up or downconverter in order to be used on a large number of applications. The experiments show a minimum conversion losses on the range of 6 to 8 dB for both applications (up and downconverter) and a 3 dB bandwidth larger then 6 GHz.<<ETX>>In this paper the design of singly balanced mixers to convert C to V band signals are presented. A step by step design technique is described, based on harmonic balance simulations. The mixer devices are Schottky diodes compatible with a GaAs MESFET technology. The mixer was optimised for minimum conversion losses on the widest possible bandwidth when used as an up or downconverter in order to be used on a large number of applications. The experiments show a minimum conversion losses on the range of 6 to 8 dB for both applications (up and downconverter) and a 3 dB bandwidth larger then 6 GHz.<<ETX>>

CMOS active inductors for L band

The implementation of CMOS active inductors at 2 GHz is described. The circuit is based on the gyrators theory. Theoretical expressions are derived with an enough accurate MOSFET model. With 0.6 /spl mu/m CMOS standard technology is possible to obtain up to a few tenth of nanohenry inductance with a Q close to 10 at 2 GHz. A MMIC was designed and the first results confirm the theoretical predictions.

Optimal design of MESFET frequency multipliers

In this paper, a design criterium for optimizing frequency doubler terminations for maximum output power (Pout) and conversion gain (Gc) is proposed. The design technique, based at a first step on linear S parameters, leads to the calculation of the MESFET terminations. Although rather simple, this approximation led to promising results: with this method, the highest output power-conversion gain trade-off ever reported was achieved and, also, the experimental and simulation results agreed closely.

Voltage controlled phase shifters on CMOS technology

Implementation of voltage controlled active inductors on standard CMOS technology for 2 GHz is described. The circuit is based on a gyrator implemented with a 5 MOSFETs feedback circuit, including the DC bias. Theoretical expressions were derived with a simple but enough accurate MOSFET model. The inductor value is controlled by an auxiliary bias voltage Vtune. An MMIC with a CMOS standard technology was designed, fabricated and tested. At 2 GHz, an L=35 nH inductor with a Qap 7 and a series resonant frequency of 2.6GHz was measured. For DeltaVtune=1.2 V, the inductor value changes from 23 nH up to 70 nH. A phase shifter application was studied: 45deg of phase shift per second order section was achieved.

K Band SiGe HBT single ended active inductors

The study of monolithic integration of active inductors (AI) on a 0.25µm SiGe BiCMOS technology with 4 metal layers and HBTs with fT=120GHz is presented. Two topologies are presented and their performance discussed. Q values higher than 30 were obtained on a 3.4GHz bandwidth at 28GHz and maximum values as high as 100. Active inductors can be biased with low power, such as 2V with a nominal DC current of 0.6mA. The inductance value is controlled by external bias voltages and adjustments up to 40% were measured. Simple gyrators topologies with only 2 transistors are used for low power consumption and good performance at K Band is proved. The internal parameters of small signal model of HBT were studied and the crucial parameter to enhance the negative resistance and so the Q of the AI was identified.

Grounded active inductors design optimization for fQmax = 14.2GHz using a 130 nm CMOS technology

This paper presents a novel design of an active inductor based on the topology of Manetakis regulated cascode active inductor. The aim of this work is to enhance the manual design of active inductors by using AIDA-C design automation methodology. The circuit is manually designed using a 130 nm CMOS technology in Cadence® to obtain an Inductor operating at 14.2GHz. The sizing of the proposed active inductor has later been optimized using AIDA-C, a state-of-the-art multi-objective multi-constraint circuit-level optimization tool. The AIDA-C circuit sizing tool was able to achieve active inductors solutions with higher quality factor, higher inductance at the operating frequency and also higher bandwidth than the manually designed solution, with the additional surplus of presenting a set of alternative Pareto optimal solutions that enables the designer to choose the most suitable circuit.

Accuracy of the Simulation of V band MMICs Typical Microstrip Elements with CAD Programs

In this paper a comparison of the simulation of MMICs typical microstrip elements, such as transmission lines, open rectangular stubs and radial stubs, with commercial CAD circuit and electromagnetic simulators with on-wafer measurements up to 70GHz, will be presented. Conclusions about the simulators accuracy and corrected models for each element will be presented.

Modelling SMD capacitor for microstrip circuits

Simple models and a parameter extraction technique for low-cost SMD capacitors mounted on microstrip lines are presented. The models are simple networks, easily implemented in currently available microwave CAD (computer-aided design) programs. Their element values are obtained from the results of vector network analyzer measurements on microstrip structures. Therefore, the models include intrinsically mounting discontinuities. The transmission line parameters values are obtained from the first series self-resonance measured for a ground connection, and the RLC parameter values are obtained from parallel resonances measured with series connection.<<ETX>>

MMIC lumped and transversal filters with Si technology

This paper describes the design and main characteristics of MMIC band pass active filters for L band. The circuits are based on the lumped and transversal concept and are implemented with standard 0.8 /spl mu/m BiCMOS process. The filters present transmission zeros close to the centre frequency to achieve a high selectivity and small bandwidth. A 3 dB bandwidth of 6% centred at 1.7 GHz and a side band rejection of 24 dB at /spl plusmn/300 MHz were the best results obtained. The circuits are biased from a 3 V power supply to be included on mobile terminals. Comparison with similar filters on GaAs is presented. Their advantages and drawbacks are discussed.This paper describes the design and main characteristics of MMIC band pass active filters for L band. The circuits are based on the lumped and transversal concept and are implemented with standard 0.8 /spl mu/m BiCMOS process. The filters present transmission zeros close to the centre frequency to achieve a high selectivity and small bandwidth. A 3 dB bandwidth of 6% centred at 1.7 GHz and a side band rejection of 24 dB at /spl plusmn/300 MHz were the best results obtained. The circuits are biased from a 3 V power supply to be included on mobile terminals. Comparison with similar filters on GaAs is presented. Their advantages and drawbacks are discussed.