A Calibrated Time Domain Envelope Measurement System for the Behavioral Modeling of Power Amplifiers

This paper presents a set-up which enables the generation and the calibrated time domain measurements of complex envelopes of modulated signals at both ports of non linear microwave power amplifiers. The architecture of the characterization tool is given. Examples of error corrected time domain envelopes at the input / output RF ports of a 36 dBm output power – 30dB power gain L-band SSPA are shown. Futhermore, the use of this characterization tool and a suitable processing of measurement data are applied to a novel measurement based behavioral modeling approach of non linear devices accounting for memory effects

Packaged Millimeter Wave Thermal MEMS Switches

This abstract describes MEMS thermally actuated millimeter wave switches. The switches are constructed using a stress controlled dielectric membrane, with patterned metallic contacts. The resulting switches can be operated at low voltage, without sacrificing the spring constant. The structure allows to build resistive switches up to millimeter wave. Full wave simulations were performed using FEM and MoM codes, and agree well with measurements. A wafer scale packaging technique has been developed to protect the components during the dicing stage, and for long term durability. The measured isolation are better than 35 dB between 30 and 40 GHz

Neural network identification and characterization of digital satellite channels: Application to fault-detection

The paper proposes a neural network technique to adaptively model and characterize digital satellite channels. The neural network model allows to identify each component of the channel by the use of the channel input-output signals as learning data. This technique was applied to fault detection in digital satellite links, especially those arising in on-board devices. The paper gives simulation examples of changes in the on-board filter characteristics. Our adaptive method allows to determine the origins of the changes and gives the new characteristics of the channel

New multipactor dynamics in presence of dielectrics

International audienceA new multipactor saturation mechanism is presented for high power microwave devices in the presence of dielectrics. Recent measures have shown that the positive charge deposited on a dielectric as a consequence of the secondary electron emission causes the reduction of its secondary electron yield. This work shows a new multipactor dynamics within a partially filled parallel-plate waveguide where both the decrease of the secondary electron yield with the charge on the dielectric and the subsequent electrostatic field produced are taken into account. The results obtained show that these two mechanisms predict the multipactor saturation as well as some differences with the classical resonance theory when charged dielectrics come into play

High bit rate four phase MMIC remodulation demodulator and modulator.

Four phase direct demodulation systems and high bit rate telemetry require four phase modulator. This work describes a four phase modulator development and a demodulator design at X-band frequency in MMIC technology. The modulator and demodulator MMIC design uses lumped elements networks and a 0.5 microns gate length process. Demodulator simulation results are presented. The modulator has been realized, it exhibits low consumption due to the use of cold FETs. Small phase switching times, less than 300 picoseconds, have been measured which confirm high bit rate modulator capability. Carrier rejection of about 28 dB and high clock rejection level are obtained in a QPSK modulation spectrum

Simplified design of microwave filters with asymmetric transfer functions

International audienceThis paper presents the design of a microwave bandpass filter having an asymmetric transfer function and a symmetric geometry. The purpose is to demonstrate that an efficient synthesis can provide simpler solutions for the hardware implementation. An example of a 6th order dual mode filter in circular waveguide technology is presented. Considering the desired topology, the initial synthesis from the Chebyshev transfer function leads to two solutions with an asymmetric electrical network. A symmetric network is then synthesised increasing the number of couplings. For one of the solutions, weak couplings can be neglected so that the transfer function is only slightly affected. The modified symmetric electrical network leads then to a simpler hardware implementation of the dual mode filter. The electrical network synthesis is described, then the optimal geometrical dimensions of the filter are determined applying an electromagnetic based optimisation method. An experimental realisation is finally compared to the theoretical results