Microwave and Millimeter Wave Electronics Laboratory
Radio Frequency CMOS Design
Despite the challenges presented by low resistivity substrates, sub-optimal active and passive devices, in recent years there has been a tremendous push to implement standard RF circuitry within low-cost digital CMOS processes. Our group is involved in this effort through the design and testing of key RF circuits such as distributed amplifiers and power combiners within standard CMOS. Success in this field requires a strong understanding of device physics, transistor-level design and an appreciation for RF and microwave circuit design concepts.
Microscope photo of a delay line implemented in a 0.5 micron CMOS process. The delay line is being probed to assess its properties for phase equalization of the gate and drain lines of a GHz distributed amplifier.
Our current efforts are focused on developing on-chip stabilization circuitry to control the performance of CMOS active inductors in Wilkinson power dividing applications.
Students involved in RF CMOS design in our group make use of several key pieces of software and test equipment including:
- Cadence, The Advanced Design System, IE3D, HFSS
- Agilent N5230A 20 GHz Four-Port Vector Network Analyzer
- Agilent N5250A 110 GHz Vector Network Analyzer
- Cascade Microtech Precision RF Probe Station
- Agilent E8251A 20 GHz Signal Generator
- An array of standard electronic bench equipment
Waveguide Based Power Combining
Due to a variety of factors, the upper millimeter and submillimeter wave ranges are compelling for implementation of a variety of electronic systems including radar, remote sensing, high capacity covert communications and chemical and biological agent detection. A fundamental challenge in realizing electronic circuitry at these frequencies is the modest output power single solid-state active devices can provide. In many instances, power combining schemes must be implemented that efficiently couple multiple solid-state devices. This research focuses on evaluating waveguide-based combining structures that can be implemented within existing micromachining processes.
LEFT: Photograph of the bottom half of an N=4 traveling wave waveguide power combiner designed for operation in X-band (8-12 GHz). RIGHT: Photograph of an assembled N=2 traveling wave waveguide power combiner ready for testing.