21-06-2012, 03:40 PM
Monolithic Microwave Integrated Circuits
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ABSTRACT
Several methods of packaging high speed (75-330 GHz) InP HEMT MMIC devices are discussed. Coplanar wire bonding is presented with measured insertion loss of less than 0.5dB and return loss better than -17 dB from DC to 110 GHz. A motherboard / daughterboard packaging scheme is presented which supports minimum loss chains of MMICs using this coplanar wire bonding method. Split waveguide block packaging approaches are presented in G-band (140-220 GHz) with two types of MMIC-waveguide transitions: E-plane probe and antipodal finline.
INTRODUCTION
In recent years, improvements in integrated circuit technologies have made robust, reproducible active monolithic microwave integrated circuits (MMICs) operating above 100GHz a reality. Such circuits enable applications in high bandwidth communications, passive remote sensing, gas analysis, and millimeter wave astronomy. Although techniques for characterization and packaging of these mm-wave MMICs can often be scaled from lower frequency approaches, for frequencies above 100 GHz their implementation can become the primary factors limiting performance and subsequent system insertion.
WIREBOND PERFORMANCE
The packaging schemes described below rely on wirebonding of the MMIC die to other components. Although this is common practice in the mm-wave circuit field, and published literature describing wirebond interfaces operating up to 40 GHz is available [3-41, we are aware of little published work characterizing such bonds up to or above 100 GHz. Here we present results of a study of coplanar wirebond interfaces between two 50n coplanar waveguide with ground (CPWG) transmission lines fabricated in the same InP HEMT process as the MMICs described in this paper.
MOTHERBOARD / DAUGHTERBOARD PACKAGING
The most commonly used methods of packaging small circuits with inputs and outputs operating at more than 100 GHz utilize waveguide interfaces. As will be discussed in the next section, the key issue with waveguide packaging schemes is the design of a transition from the waveguide modes to the CPWG or microstrip environments typically used on the integrated circuit chips.
Here we present an alternative packaging scheme that can be used for systems in which many MMIC die are to be chained end-to-end, in which these waveguide transitions are avoided, thereby minimizing the loss and volume associated with the packaging. This situation is not uncommon, as low yield of extremely high frequency, high performance devices is common, making monolithic integration of such a chain of MMICs difficult or impossible.