Integrated Multifunction X-Band MMIC Merges Microwave And Digital Control Functions

Advanced multifunction self-aligned gate (MSAG) process technology enables the merging of microwave and digital control elements onto a single MMIC device. In the discussion below, an X-band control MMIC with seven stages of gain, six-bits each of phase and attenuation control, transmit/receive switching and an onboard serial-to-parallel controller is presented. When combined with a M/A-COM integrated 10 W limiter/LNA and 20 W HPA MMIC, the three GaAs MMIC chipset provides a low-cost, high-performance solution to X-band phased array radar front-end needs.

Cost is a significant driver in the development of phased array systems, where modests savings at the module level can result in significant savings at the array level. In a multichip module, monolithic microwave integrated circuit (MMIC) related costs can be significantly more than just the cost of the MMIC die, when factors such as off-chip components and assembly costs are taken into account. Multifunction MMICs can directly reduce cost through reduced MMIC die count and associated off-chip components and bond wires, while at the same time providing indirect savings through improved module yield and reliability. The purpose of this article is to describe the latest efforts by M/A-COM to provide highly integrated multifunction control MMICs, or MCMs, for phased array applications. The vehicle presented is a seven-gain stage design with six bits each of phase and attenuation control, transmit/receive (Tx/Rx) switching and an onboard serial-to-parallel controller (SPC). To our knowledge, this represents the highest level of integration available in the market for a standard gallium arsenide (GaAs)-based Tx/Rx MMIC for phased array applications.