Event - 31 January 2024

PhD Defence: CMOS Terahertz Systems: From Circuits to Applications

Lectured by Gabriel Guimaraes


Speed scaling has mostly stopped as the overall circuit speed is limited by the interconnect. Nevertheless, THz frequencies (>300 GHz) have been demonstrated in CMOS. To achieve this, designers rely more and more on innovative circuit techniques to create and detect signals. It is in this context that this thesis is placed, as its first focus is circuit techniques for the generation of terahertz frequencies in CMOS devices. The other focus is novel applications that are enabled by these circuits in this novel electromagnetic spectrum. The thesis starts by describing the basic performance limitations of circuit devices in the mm-wave and terahertz regions. After this, single elements terahertz sources are mathematically described and a 570 GHz is demonstrated in 40 nm CMOS Technology. The thesis then extends this concept into THz arrays. The basic theory for these arrays is discussed and a highly integrated oscillator-radiator array operating at 670 GHz is presented.

After that, wideband mm-wave amplifiers are analyzed. These blocks are fundamental to THz system design as they are often present within multiplying chains or transceivers. The design of these amplifiers can particularly benefit from automated layout and optimization and this is the approach taken in this work. Two different amplifier designs are presented: The first is a general-purpose wideband amplifier around 200 GHz. The second is a pair of similar low-noise amplifiers designed for a dual-band communication system using 28 nm technology.

The second part of the thesis is focused on mm-wave and terahertz applications. We present the theory of gas rotation spectroscopy and system-level considerations when designing a mm-wave spectroscopy system. A transmitter and receiver for spectroscopy at D-band designed in 28 nm CMOS is presented, and a simple spectroscopy setup is assembled to demonstrate its use.


31/1/2024 13:30 - 15:30


ESAT Aula C, B91.300