Gambie - structures économiques et problèmes de développement = Gambia - economic structures and development problems. VIII/1026(72)-F/B3

An original topology of GaAs-PHEMT mixer is investigated under high conversion gain consideration.Mixer topology is based on "LO source-injection"concept,since RF, IF and LO signals are respectively applied on the gate,drain and source terminals of the mixing transistor.The conversion matrix formalism allows both the optimization of matching and filtering cells and the assessment of the nonlinear stability.For 14 to 12 GHz frequency conversion, the designed MMIC single balanced mixer exhibits a conversion gain of 5 dB at -15 dBm LO power for a total power consumption of 88 mW and chip size about 0.9 mm 2. The other performances are an output IP3 of 7 dBm for –8 dBm LO Power and a NF of 7 dB

Bulk Silicon Micro-Machined MEM Switches For Millimeter-Wave Applications

ABSTRACT This paper deals with the realization of micro-electro-mechanical (MEM) components dedicated to microwave and millimeter-wave applications and focuses on the advantage of using bulk silicon micro-machining. The silicon substrate etching benefits have been demonstrated through both electromagnetic simulations and measurements of a single MEM switch. Important improvements in term of insertion loss and isolation have been obtained. Further developments in term of distributed switches are addressed

Bulk Silicon Micro-Machined MEM Switches For Millimeter-wave Applications

This paper deals with the realization of micro-electro-mechanical (MEM) components dedicated to microwave and millimeter-wave applications and focuses on the advantage of using bulk silicon micro-machining. The silicon substrate etching benefits have been demonstrated through both electromagnetic simulations and measurements of a single MEM switch. Important improvements in term of insertion loss and isolation have been obtained. Further developments in term of distributed switches are addressed

The Reliability of III-V semiconductor Heterojunction Bipolar Transistors

The Heterojunction Bipolar Transistor (HBT) features some characteristics that make it a very promising device in the telecom field. For these applications, the reliability is a key issue. The aim of the present paper is to summarise the most relevant reliability concerns, from whose the HBT suffers, as the stability of the ohmic contact, the presence of defects, and the stability of the base dopant. Since in the last years the Si/SiGe HBT has emerged as a strong competitor against the III-V HBT, a paragraph has been devoted to summarise the reliability concerns of the Si/SiGe HBT

Small-signal model extraction technique dedicated to noise behaviour of microwave HBTs

A complete on-wafer heterojunction bipolar transistors (HBTs) equivalent circuit parameters extraction technique is presented. It is based on the successive extraction of extrinsic and intrinsic elements. An improved method for parasitic inductance values determination is proposed. It results in a more accurate modelling of HBTs which is shown to be very useful especially for high frequency noise parameter modelling

Low frequency noise conversion in fets under nonlinear operation

Based upon the active line concept, the conversion mechanisms of microscopic low frequency noise (e.g. generation-recombination noise) located in the channel of a Field Effect Transistor (FET) which is driven by a large RF signal is demonstrated. The first consequence is that the based band (low frequency) input gate noise voltage spectral density is dependent on the magnitude of the input RF power applied to the FET. Moreover, the microscopic generation-recombination noise sources located in the channel are responsible of up-converted input gate noise voltage spectral density around the RF frequency

Frequency synthesis from 2 to 30 GHz using a 0.35 µm BiCMOS SiGe technology

In this paper, we present a 10/30GHz MMIC Tripler, an X-band VCO and a frequency divider using a 0.35 µm, 60 GHz-fMAX MMIC BiCMOS SiGe technology. The Tripler exhibits a conversion gain of -5 dB and a low additive phase noise of –143dBc/Hz at a frequency offset of 100kHz is anticipated. In order to drive this Tripler, the design of a MMIC X-band VCO and its measured performance (0.8GHz tuning range, -5 dBm output power and –87dBc/Hz phase noise @ 100kHz of carrier) is also reported. This X band VCO can also drive a frequency divider, developed in the same technology. The assembling of these circuits allows the design of a 2 GHz frequency synthesizer. Measurements have shown a phase noise of -99dBc/ Hz at a frequency offset of 100kHz. Therefore, this paper demonstrates the great capabilities of BiCMOS SiGe MMIC technology about frequency synthesis ranging from 2GHz to 30GHz

Driver for phase shift keying modulator using a multilevel MMIC technology for K-band space applications

This paper presents a new simple design of an integrated driver using a multilevel MMIC technology that can be used to operate a NRZ (No Return to Zero of digits) two, four or eight phase shift keying direct modulator. It can be fed by any digital signals featuring any low level (VOutput Low) between 0 V and 0.5 V and a high level (VOutput High) between 2.5 V and 8 V. It therefore provides a full compatibility with most usual logic families. An MMIC featuring a K-band (17.5 to 21.5 GHz) Bi-Phase Shift Keying modulator (BPSK) along with the proposed driver has been designed. The measured performances are : 6° maximum phase error and 1.1 dB maximum amplitude error over the full 4 GHz bandwidth

Highly compact micro-machined coplanar bandpass filter

Highly compact micro-machined coplanar bandpass filters based on end-coupled half-wavelength and quarter-wavelength resonators topologies have been investigated. Simple gap and interdigitated capacitive discontinuities have been modeled through an appropriate technique and have been implemented in order to achieve low loss and narrow bandpass membrane micromachined filters.Excellent performances,similar to the state of the art, together with an important improvement in term of compactness have been achieved

Correlation between kink effect and frequency dispersion in pseudomorphic HEMTs

This paper presents DC and AC frequency dispersion effects of the drain-source output impedance in commercially available pseudomorphic HEMTs. Inductive behaviour observed on the imaginary part of the drain-source impedance is attributed to deep traps in the GaAs substrate from DC and AC measurements versus temperature. On the other hand. DC and AC measurements indicate that kink effect signature is related to impact ionisation at the drain edge of the gate followed by trapping-detrapping processes in the substrate