This paper describes a multichip module technology based on highly impermeable liquid crystal polymers (LCP's) to interconnect and package monolithic microwave integrated circuits (MMIC's). Because of the low moisture permeability of the LCP's, the packages can be made hermetic without heavy expensive housings and can be two to four times lighter and onefifth the cost of conventional ceramic based transmiVreceive (T/R) modules. The LCP material has a low dielectric constant (2.65) and low-loss tangent and is manufacturable using high volume, large-area processing methods that provide very reliable highperformance circuits at low cost. Using flip-chip bonded MMIC's attached to a high thermal conductivity, low coefficient of thermal expansion substrate, this innovative technology can meet a variety of commercial, military, and NASA requirements.
We report a fully packaged AlGaAs waveguide modulator array with four individually addressable elements operating at approximately 830 nm wavelength and a clock speed of 1 GHz. The modulators rely largely on the linear electro-optic effect for operation, and have been packaged with an E/D MESFET driver with complementary 3.5 V outputs, and a thick-film ceramic bias network. The device is compact, using multimode interference devices for on-chip splitters and combiners and has a 4 mm electrode length. Extinction ratios in excess of 10 dB have been demonstrated over a temperature range from m m temperature to 143°C. The modulator array has been packaged with a remote high power (100 mw) diode laser using stable single mode input coupling, while the modulator output is packaged with a multimode fiber array of 62.5 pm core diameter.
Due to the increasing demand for fast data rates and large spectra, millimeter-wave technology plays a vital role in the advancement of 5G communication. The idea behind Mm-Wave communications is to take advantage of the huge and unexploited bandwidth to cope with future multigigabit-per-second mobile data rates, imaging, and multimedia applications. In Mm-Wave systems, digital precoding provides optimal performance at the cost of complexity and power consumption. Therefore, hybrid precoding, i.e., analog–digital precoding, has received significant consideration as a favorable alternative to digital precoding. The conventional methods related to hybrid precoding suffer from low spectral efficiency and large processing time due to nested loops and the number of iterations. A manifold optimization-based algorithm using the gradient method is proposed to increase the spectral efficiency to be near optimal and to speed up the processing speed. A comparison of performances is shown using the simulation outcomes of the proposed work and those of the existing techniques.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.