David A. Willems

N-Way MMIC Redundant Switch

A novel approach to provide redundancy in an N-Way MESFET Switch has been invented and realized with monolithic microwave integrated circuit technology. This switch circuit uses series and shunt FETs configured in a manner to prevent failure of the switch even if several FETs fail. For example a SPDT redundant switch is capable of providing 1.3 dB insertion loss, and return loss and isolation better than 20 dB and 35 dB, respectively over dc to 12 GHz, even if 25% of the FETs fail in each arm.

An MMIC-compatible tightly coupled line structure using embedded microstrip

The authors present a highly manufacturable coupled line structure for MMICs (monolithic microwave integrated circuits) which uses embedded microstrip to achieve tight coupling and only uses the process steps necessary to make MIM (metal-insulator-metal) capacitors. Passive circuits demonstrated using this technique include a single-section 5-21-GHz broadband 3-dB coupler and a 6-15-GHz 90 degrees Schiffman section. The coupler and the Schiffman section use tight (2-dB) to extremely tight (0.7-dB) coupling factors, respectively. This is the first time that a coupler has achieved such a wide bandwidth on a 125- mu m-thick GaAs substrate. >

Multifunction small-signal chip set for transmit/receive modules

Design and test results for small-signal multifunction MMICs (monolithic microwave integrated circuits) for C-band transmit/receive (T/R) modules are presented. This chip set includes the entire receive path and a portion of the transmit path (seven stages of amplification and 11 passive circuits) in just four chips. These ICs, fabricated with the multifunction self-aligned gate (MSAG) process, demonstrate a high level of integration, excellent performance, and a good yield. The variable-gain low-noise amplifier has 30+or-1 dB gain and 2.5 dB noise figure, the phase shifter SPDT (single-pole double-throw) switch has 8+or-1 dB loss, the T/R buffer amplifier has 6.5+or-0.2 gain and 3.5 dB noise figure, and the variable gain buffer amplifier has 8.5+or-0.5 dB gain and 2.5 dB noise figure. >

A quasi-microstrip traveling-wave power divider/combiner for use in high-density packages

A low-loss miniature microstrip four-way traveling-wave divider/combiner (TWD/C) that incorporates the package effects in the circuit design, i.e. the microstrip transmission line impedances partially include the package wall as a ground plane, is presented. The TWD/C was designed using a full-wave electromagnetic simulator. It has less than a 0.3-dB insertion loss and a 1.6:1 VSWR at all ports over a 6-GHz bandwidth.<<ETX>>

Accurate design of multiport low-noise MMICs up to 20 GHz

This paper presents a novel noise parameter extraction technique for MESFETs. All measurements are done with a 50 ohm source and load which allow the FET to be characterized on wafer easily, accurately and quickly. The noise parameter values are extracted using an in-house model extraction CAD tool. This technique has been validated by comparison to noise parameters measured by using tuners. Additionally, LNAs, distributed and feedback amplifier MMICs have been tested and demonstrated excellent correlations between the measured and simulated noise performance up to 20 GHz.