Design And Research Of Chip Level Microwave Switch And Tunable Filter Using GaAs Process

With the continuous advancement and innovation of science and technology,people have increasingly strict requirements for RF components in communication systems.In microwave millimeter wave systems,RF switches and tunable filters are considered important components in RF front-end systems.RF switches are widely used to control microwave signal paths in radar and communication systems.However,with the increase of the operating frequency and complexity of the system,radio frequency switches are required to have good performance and easy integration characteristics.Reconfigurable filters have been researched by scholars because the reconfigurable filters be able to achieve the characteristics of adjustable center frequency,adjustable working bandwidth,and adjustable transmission zero.Using traditional design methods,the two components are considered difficult to achieve compact size with low insertion loss and ultra-wideband.In this thesis,optimization studies are performed to achieve miniaturization as much as possible while maintaining the high electromagnetic characteristics of RF switches and reconfigurable filters.Nowadays,RF components are developing in the direction of high integration,high power,and wide frequency band.The microwave monolithic integrated circuit(MMIC)is proposed because of its higher integration and mature technology to meet current design requirements.The advantages of high speed,low dielectric loss and high reliability are available in GaAs MMIC.Especially in recent years,the production cost of GaAs technology also been reduced,its application range is also increasing.This article is based on the 0.25um GaAs pHMET process.The MMIC single-pole double-throw switch chip and two reconfigurable on-chip filters are designed and developed.The main work of the paper is as follows:First,a compact ultra-wideband single-pole double-throw switch chip with low insertion loss and high isolation is proposed.In this paper,a new type of?-type topology is used,which is composed of a short transmission line and two metal-insulator-metal(MIM)capacitors in parallel.This?-type topology is used to replace a quarter-wavelength line connecting two parallel transistors.Compared with traditional methods,this new?-type topology be able to connect more transistors in parallel in a smaller size,thereby achieving ultra-wideband and high isolation performance.A chip sample is fabricated with a size of 1.25×1.05 mm2.The measured insertion loss is less than 1.8 dB and the isolation is better than 36 dB from DC to30 GHz.Good agreements are observed between the simulated and measured results.Both tunable band-pass filters are third-order capacitively coupled structures,and their operating frequency bands are tuned by transistors and their corresponding gate bias circuits.Due to the low Q value of the spiral inductance in the GaAs process and the large occupied area,the lumped LC resonators in this paper are replaced by semi-lumped resonators.The semi-lumped resonator is composed of metal stubs and MIM capacitors,which can overcome the disadvantage of on-chip spiral inductors and achieve a more compact size.Among the two tunable filters:the first is the MMIC bandpass filter of the tunable frequency band,and its size is only 0.08×0.11?g~2.This filter is switched in two frequency bands:one frequency band is centered at 10 GHz with a fractional bandwidth(FBW)of 24.94%;the other is centered at8.8 GHz with a FBW of 13.35%.The second is a tunable bandwidth MMIC bandpass filter,and its size is only 0.086×0.095?g~2.The reconfigurable filter works in two modes,and the center frequency of both modes is at 10 GHz:the FBW of one mode is 23%;the FBW of the other mode is 14%.