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Proceedings Paper

Device and packaging considerations for MMIC-based millimeter-wave quasi-optical amplifier arrays
Author(s): Nicholas J. Kolias; Thomas E. Kazior; Yan Chen; Warren Wright
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Paper Abstract

Practical implementation of millimeter-wave quasi-optical amplifier arrays will require high device uniformity across the array, efficient coupling to and from each gain device, good device-to-device isolation, and efficient heat removal. This paper presents techniques that address these issues for a 44 GHz MMIC-based design. To improve device uniformity, a double selective gate recess approach is introduced which results in a demonstrated 3 - 5X improvement in uniformity when compared to Raytheon's standard production pHEMT process. For packaging, direct backside interconnect technology (DBIT) is introduced as a bondwire-free scheme for connecting each amplifier to the array. This approach significantly reduces interconnect loss by reducing interconnect inductance. Measured insertion loss at 44 GHz for the DBIt transition is 0.35 dB compared to 2.3 dB for a typical bondwire transition produced on a manufacturing automated bonding machine. By eliminating bondwires which tend to radiate at millimeter wave frequencies, the DBIT approach also significantly improves the device-to-device isolation, thereby improving the array stability. The DBIT approach would not be viable if it could not effectively dissipate heat (a typical 25 watt array generates greater than 100 watts of heat). Finite element thermal analysis results are presented which show that the DBIT approach adds a tolerable 15.5 degree(s)C temperature rise over a standard solder-based MMIC die-attach to a heatsink. Thus, the DBIT approach, along with the double selective gate recess process, provides an attractive, low-loss, bondwire-free approach for producing uniform amplifier arrays.

Paper Details

Date Published: 12 November 1999
PDF: 8 pages
Proc. SPIE 3795, Terahertz and Gigahertz Photonics, (12 November 1999); doi: 10.1117/12.370164
Show Author Affiliations
Nicholas J. Kolias, Raytheon Co. (United States)
Thomas E. Kazior, Raytheon Co. (United States)
Yan Chen, Raytheon Co. (United States)
Warren Wright, Cornell Univ. (United States)


Published in SPIE Proceedings Vol. 3795:
Terahertz and Gigahertz Photonics
R. Jennifer Hwu; Ke Wu, Editor(s)

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