A 1-Watt Ku-Band Power Amplifier MMIC Using A Cost-Effective Organic SMD Package

Abstract -- This paper presents the design and performance of a compact 1-Watt Ku-band power amplifier MMIC implemented in a novel microwave organic power package, compatible with SMD assembly lines. Due to the use of simple materials, like RO4003 substrate and copper, it allows significant cost reduction for RF module assembly. The packaged amplifier MMIC demonstrates as well, very high-gain, as high as 32 dB at Ku-band, under very stable conditions, and more than 1.25-Watt continuous-wave output power (>31 dBm).

Introduction

Despite of today's economic situation in telecommunications, recent growths in the VSAT (very small aperture terminals) market have created a demand for low cost high power amplifier solutions in the Ku- and Ka-bands. Furthermore, the trend of microwave and millimeter wave ICs is now toward cost effective packaged products, compatible with Surface Mount Device (SMD) assembly lines. Module manufacturers have indeed to reduce their assembly cost to a minimum, to be competitive, increasing further the pressure on MMIC manufacturers. Although chip size reduction, and the use of multifunction MMICs help to reduce the cost, the assembly contribution on module level is however still significant. This is especially due to the expensive pick- and place equipments, bonding tools, clean room installation, etc.

However, one of the biggest challenges for packaged high power microwave amplifiers, is the thermal management at the lower cost. Among the number of existing packages available for microwave devices like flange mount-, ball grid array-, quad flat packages (micro leadframe or QFN), ceramic- or silicon packages, one promising approach is the organic PCB (Printed Circuit Board) power package technology developed by Labtech. within the European SMACKS project. The MMIC is attached onto a thickened copper slug (120 µm), within a cavity made in low-cost 8-mils RO4003 substrate (203 µm). The electrical interconnects are realized with gold bond wires connecting the MMIC pads to feed lines on the package frontside, themselves connected to the package leads, through the package substrate by mean of RF vias. After covering with a lid, the device can be mounted, by a reflow soldering technique for instance.