Ultra-broad bandwidth and low-loss GCPW-MS transitions on low- k substrates

Abstract

International audienceA study of back-to-back grounded coplanar waveguide-microstrip (GCPW-MS) transitions is presented. By using low-permittivity substrates, both the attenuation and the bandwidth can be improved. An ultra-broad bandwidth up to 77 GHz could be obtained with the BCB polymer as substrate in thin film on low-resistivity silicon wafers

Coplanar-Microstrip Transitions for Ultra-Wideband Communications

“…Indeed, low permittivity obtained by micromachining substrates allows to get low-dispersive waveguides (quasi TEM approximation) and to realize coplanar transmission lines with very high bandwidth without excessive dispersion and loss (Newham, 2006). The main reason for the high cut-off frequency improvement of GCPW-MS-GCPW transitions is that the guided wavelength is bigger in low-k substrate for a given frequency, so the parasitic resonance between the backside conductor and the coplanar ground strips takes place at higher frequency (El-Gibari, et al, 2010a). In addition, as for low effective permittivities a large part of the energy is propagating in air medium, so losses can be minimized.…”

Coplanar-PGL Transitions on High Resistivity Silicon Substrate in the 57-64 GHZ Band and Influence of the Probe Station on the Performances

“…A transition, from coplanar waveguide to dielectric waveguide, is investigated for the integration of active devices in dielectric waveguides, and allows a maximum insertion loss of 1.7 dB and return loss better than 15 dB over 7% bandwidth at 60 GHz for a total length of 7 mm [10]. Grounded Coplanar Waveguide-Microstrip (GCPW-MS) transition on 8 µm-thick BCB deposited on a metalized low resistivity wafers for a 1 cm back-to-back structure can facilitate the characterization of components driven by MS transmission lines up to 77 GHz with insertion loss better than 2 dB [11].…”

“…The PGL lines have already been characterized for higher frequencies by means of transitions: PGL to 50 Ω microstrip line circuit transitions on ceramic substrate (0.254 mm alumina), dedicated to feed PGL loads and power divider/combiner, present, for a 16 mm total length of the back-to-back structure, a 4 dB transmission parameter from 40 GHz to 60 GHz [12], or dedicated to feed couplers with short range (60 GHz) radio [13], a coplanar-Goubau Line transition on Duroid 5880 provides a 5-10 dB insertion loss and a return loss better than −12 dB from 140 GHz to 220 GHz for a back-to-back structure [14] and recently a "smooth" transition to match a periodic leaky-wave antenna at millimeter wave frequencies with PGL impedance to a coplanar waveguide [15]. The results for the transitions to excite the PGL mode [12][13][14][15] seem less efficiency than for the other ones [2][3][4][5][6][7][8][9][10][11]: the PGL doesn't need a ground plane, contrary to the coplanar or micro-strip modes and the conversion from coplanar or micro-strip modes to PGL mode generates other modes or losses.…”

Design of Mach-Zehnder interference modulators composed of enhanced electro-optic active polymers

“…We also designed a low loss Mach-Zehnder interference (MZI) with high bandwidth using the novel polymers 5 . Structures of waveguide and traveling wave electrodes, such as the coplanar waveguide electrodes (CPWE) and the micro-strip electrodes 6,7 (MSE), were optimized to improve the performance of the modulator.…”