Dean Paul Kossives

Design and characterization of multilayer spiral transmission-line baluns

We discuss the design of coupled spiral transmission-line baluns modeled after the Marchand type. The balun structure consists of a pair of coupled spiral conductors vertically offset across intervening polyimide layers. The baluns are fabricated on various substrates (glass and high- and low-resistivity silicon). The characteristics such as return loss, insertion loss, and output signal imbalance are measured. The center frequencies of 3-dB bandwidths (BWs), primarily determined by their conductor lengths, range from 1.2 to 3.5 GHz. The 3-dB BW normalized by the center frequency is /spl sim/1.48 in all cases. We observe an optimum BW for better performance. Return losses at the center frequencies range from 13 to 18 dB. Amplitude imbalance distributes in the range of 0.3-1.0 dB, depending on the sizes of devices and substrates. The minimum insertion loss is 0.55 dB for the balun on a glass substrate with 100-/spl mu/m-wide conductors. The devices fabricated on glass and high resistivity (>4000 n cm) silicon show remarkably similar behaviors despite the large difference in dielectric constant. This technique is applicable to monolithic microwave integrated circuits.

High Q-factor inductors integrated on MCM Si substrates

High quality factor (Q) inductors were designed and fabricated on high-resistivity (2000 /spl Omega//spl middot/cm) Si substrates with multichip module (MCM) fabrication technology. A Q-factor of 30 was achieved for an inductor of 4 nH at 1-2 GHz. To enhance the Q-factor and reduce the parasitic coupling capacitance, a staggered double metal-layered structure was utilized by taking advantage of the double-layered metal lines in MCM. With electromagnetic simulation tools, computer-aided analysis was used to optimize the device characteristics. The skin effect and the lossy substrate effect on the performance of the radio frequency (RF) thin-film inductors were studied. The fabrication process used polyimide as the dielectric layer and aluminum as the metal layer. The use of the low dielectric-constant material, polyimide, reduces the parasitic coupling capacitance between metal lines and increases the quality factor and the self-resonant frequency for the RF integrated inductors.

High quality-factor inductors integrated on Si multichip modules

We report high quality (Q) factor inductors fabricated on a high-resistivity (2000 /spl Omega/-cm) Si substrate with MCM technology. Q-factors of 30-40 were achieved for inductors of a few nH at 1 GHz.