High-Frequency Electronics

Summary

The High-Frequency Electronics project supports advanced communications, millimeter-wave technologies, quantum computing, and the semiconductor industry through research of high-frequency on-wafer metrology and the development of electronics-based metrology instrumentation. This work spans the application of accurate measurement techniques and characterization methods to on-wafer and over-the-air (OTA) components; design and characterization of high-frequency circuits realized using cutting-edge technologies; and extending the application of accurate electronic instrumentation to ever more complicated applications. Ultimately, the work in this project facilitates the adoption of new technology by industry by providing accurate assessments and improved techniques and models to be used in design and integration.

Description

This project supports the metrology of advanced electronic circuits and systems through many activities centered around accurate measurements and characterizations, improving device models and designs, enabling traceability of complicated electronics systems, and incorporating advanced technologies such as new semiconductor technologies, optoelectronics, and quantum measurements.

Activities

Development of instrumentation and techniques for advanced on-wafer measurements: One of the thrusts of this project is to develop new instrumentation and techniques to support on-wafer characterization. On-wafer characterization of high-frequency electronics requires precision in the definition of calibration structures. We develop new on-wafer calibration structures and calibration procedures for THz frequencies, with the objective to reduce measurements errors. Additionally, an on-wafer phase reference is required to enable non-linear characterization of such circuits.  Recently, we’ve created a millimeter-wave on-wafer phase reference to enable accurate phase characterization across frequency enabling the characterization of active devices.

Measurement, modeling and design of optoelectronic devices and systems: We incorporate electro-optic techniques to develop new methodologies and instrumentation for characterizing high-frequency electronic systems. Here, we have worked to develop an ultra-wideband THz arbitrary waveform synthesizer that uses extremely-precise optical sources to interrogate electronic devices.

Measurement, modeling and design of electronic devices and systems: Another thrust of this project is to develop improved techniques for the measurement and modeling and design of cutting-edge high-frequency electronic circuits. The adoption of such technologies relies on accurate and robust circuit models and accurate characterizations. This project works to increase the accuracy of active device models and incorporate measurement uncertainty and process variation into the design process leading to more robust circuit designs. These improvements may enable new technologies by reducing the time to design success and improving yields of advanced circuits. Ultimately, these improvements may enable new applications by facilitating the adoption of these advanced technologies.

ELectronics for G-band Arrays (DARPA): We are applying our measurement, calibration and characterization expertise to help evaluate the performance of next generation G-band (170 to 260 GHz) circuits designed for communication. These circuits include power amplifiers in bleeding-edge III-V technologies. As part of our partnership with commercial foundries we provide guidance on calibration methodologies and design techniques. Additionally, we are an independent evaluator of fabricated circuits for this program. Through this work we are directly improving industry’s understanding of their own fabrication technology.

Electronic calibration for cyrogenic quantum systems: Many quantum applications require accurate microwave measurements at cryogenic temperatures and these applications would benefit from applying standard room-temperature calibration methods. However, the complicated cryogenic dewars and dilution refrigerators used in many quantum applications place serious constraints on the ability to perform calibrations in these restrictive environments. Recently, we’ve accomplished a VNA calibration at an on-wafer reference plane at 4 K inside of a dewar. This calibration required multiple on-wafer measurements and landing measurement probes precisely without optics to guide the positioning.

Over-the-Air measurements and traceability: As the communications industry moves to more compact and embedded circuitry, connectorized RF test ports are often unavailable. Nevertheless, industry demands testing methodologies which must now be performed over-the-air. This project supports these efforts by extending our calibration expertise to produce traceable over-the-air measurements. This work enables the accurate characterization of next generation wireless communications systems.

Traceable electronic characterization: The High-Frequency Electronics project has pioneered traceable electrical measurements of devices and systems. These traceable measurements are directly related to fundamental physical quantities, such as the meter and second, and accompanied with an evaluation of uncertainty. To accomplish this, many measurement systems and calibrations must be linked to preserve traceability throughout complicated measurement chains. Specifically, measurements taken using the electro-optic sampling system provide traceable phase, while traceable impedance is provided using vector network analysis and dimensionally-traceable calibration standards – two separate methodologies and laboratories. To obtain system level measurement traceability, measurements from several such laboratories must be combined in concert and a consistent uncertainty analysis applied throughout the entire measurement chain.

Current Measurement Capabilities

In our laboratory we use wafer probe-stations, frequency extender heads ranging from DC to 1 THz, and optical frequency combs with terahertz optoelectronics. We use load-pull systems to characterize active devices (such as power amplifiers) in the presence of output impedance mismatch. We have a pulsed IV system which we use to measure active on-wafer devices to determine the performance of semiconductor devices while avoiding self-heating and trapped charges. Additionally, we also have a dilution refrigerator which we have used to move microwave reference planes down to cryogenic temperatures (4 mK).

Our measurements use advanced calibration algorithms and de-embedding techniques to accurately characterize passive and active devices, sources, and receivers. We de-embed measurements and characterizations to arbitrary reference planes and impedances and apply robust uncertainty analyses to all our measurements and characterizations. 

List of our current measurement capability

• Scattering parameters to 1.1 THz
• Large Signal characterization to 50 GHz
• Multi-harmonic load pull to 40 GHz
• Pulse IV system
• Cryogenic probe station
• Electro-optic sampling

Major Accomplishments

• Demonstrated an on-wafer phase reference above 110 GHz
• Developed innovative electronic integrated circuit for new instrumentation
• On-wafer calibration at cryogenic temperatures