Design, 3D Electromagnetic Simulation and Implementation of Ceramic Package for GaAs Monolithic Microwave Integrated Circuits based x-band receiver application

Abstract

 In this paper designing of a ceramic package, 3D electromagnetic simulation-based modelling of the package, fabrication of the package and validation of the package to meet the challenging requirements of light weight and low-cost package is described. Proposed package modelling is carried out in wideband frequency range to have lower impact on the MMIC with lower parasitic in RF path and interconnection in the RF path. This package is suitable for low noise amplifier packaging as well as high gain MMIC amplifier packaging. Wideband analysis helps to understand the out of the band behaviour of the package. Optimized transitions with minimal parasitic effects on GaAs MMIC is also optimized and presented. This is a 7x7 ceramic package having 48-pins. This proposed package structure is embedded with GaAs MMICs working before the cut-off frequency of the package. For proper package grounding the base metal is selected with optimized enough number of packed via holes. Base metals as well as the package 48 pins are gold plated to outfit for MMICs die bonding and also for 1 mil gold wire bonding. Package 48 pins are having 0.3mm pins width and 0.2mm pins spacing between the pins and distributed along four sides equally with no leads. This without leads pin packaging QFN structure gives suitable outputs at microwave frequency which is due to pins lower inductance and higher pins isolation. This proposed ceramic package structure shows lower electromagnetic interference (EMI) and electromagnetic coupling (EMC) between pins as well as the dies. MMICs functional testing is carried by attaching this package on a separate test structure planned for RF lines and DC lines. Fabricated input and output lines on FR4 material with properly designed model suitable for microwave frequency band. This ceramic package is 3D EM simulated using CST microwave studio software. This ceramic package having 50-ohm transmission lines fabricated using thin-film technology. Input and Output RF connectors are also working in wideband frequency range. S₁₁, S₂₂, S₂₁ as well as NF are recorded for the proposed package structure on open and closed packaging conditions. Ceramic package measurements resulted with S₂₁ of 23dB (typical), return losses are lower than 10 dB and NF 2.5dB. These results are in line with simulation data of the MMICs. Gain flatness in this frequency band is better than ±0.3dB. Noise figure flatness is better than ±0.05dB.