Design Techniques and Measurement Methods for Broadband Millimeter-Wave and THz Systems in Silicon
Doctor of Philosophy
Short impulses in millimeter-wave (mm-wave) and THz regimes (30 GHz - 30 THz) have a potentially large bandwidth that can be exploited for various applications, for example, high-resolution 3D imaging, high-speed wireless communication, broadband spectroscopy, etc. Existing methods for impulse generation have the following drawbacks: First, photonics solutions are usually not compatible with silicon technologies, i.e. CMOS and BiCMOS, impeding higher level SOC designs; Second, electronic oscillator-based solutions usually require phase-locked loop (PLL) and delay-locked loop (DLL) to ensure coherency of generated impulses, which increases system complexity, power consumption, and die area; Third, electronics digital-to-impulse solutions can be further improved by generating shorter impulses, reducing late-time ringing, and achieving amplitude modulation. In addition, high demands on using silicon technology to generate picosecond or sub-picosecond impulses impose challenges on standard chip characterization methods in both time domain and frequency domain. This dissertation demonstrates three chip designs and one chip characterization method to resolve the aforementioned drawbacks and challenges. The first chip design is to use a CMOS-compatible silicon photonics process technology to design a THz PCA chip, which can radiate 1.14 ps impulses. The prototype silicon photonics chip enables easier integrations with other photonics and electronics devices on a single chip. The second chip design is to implement an asymmetric-VCO-based impulse radiator without requiring any PLL or DLL in a 130 nm SiGe BiCMOS. With on-chip antennas, it radiates 60 ps impulses with less power consumption, system complexity, and die area than conventional oscillator-based solutions. The designed impulse radiator has also been applied for 3D imaging. The last chip design is to apply a new circuit technique, nonlinear Q-switching impedance, to implement a 4 ps impulse radiator with pulse amplitude modulation in a 130 nm SiGe BiCMOS. An optoelectronics-based time-domain characterization method was invented to test the 4 ps impulse radiator, and this new measurement technique shows a significant accuracy improvement compared with standard time-domain methods. The demonstrated techniques in this dissertation show that silicon technology is a promising solution to generating picosecond and even sub-picosecond impulses and it is approaching to the performance of photonics devices. Ultra-broadband silicon-based impulse radiators can be characterized using optoelectronics technology to achieve better measurement accuracy.