| dc.description.abstract | The Q-band (33-50.5 GHz) in the millimeter-wave spectrum has
been widely applied in recent years due to its large bandwidth, faster
transmission rates, and lower latency. Applications of the Q-band include
weather radar, fth-generation (5G) mobile communications, and
emerging satellite internet. In these applications, phased arrays and amplifiers play critical roles in transceiver architectures. The phase shifter
is particularly crucial in phased arrays, providing adjustable phase differences
to the antennas within the array, thereby altering the transmission
and reception directions for precise beam control and exible
communication operations.
In Chapter 2, we implemented a fully dierential 6-bit passive phase
shifter for the Q-band (center frequency designed at 38 GHz) using
TSMC 90-nm CMOS technology. Both the analog and digital phase
shifting stages of this circuit are realized using transmission line-based
all-pass networks. These stages are cascaded with dierent center frequencies,
enabling broadband performance. Phase shifts below 45◦, including
22.5◦, 11.5◦, and 5.625◦, are achieved with analog phase shifters,
controlled digitally by a 3-bit digital potentiometer (DPOT). The analog
phase shifter utilizes MOS varactors to achieve the desired phase shift
within a speci ed voltage range. Despite the poorer linearity of analog
phase shifters, a single-stage analog phase shifter can replace three
stages of digital phase shifters, reducing insertion loss. To achieve 360◦
phase shift, a pair of single-pole double-throw (SPDT) switches is used for the fi nal 180◦ phase shift. This design minimizes circuit area and
insertion loss while maintaining broadband performance.
Chapter 3 explores the design of a Q-band GaAs all-pass network
phase shifter. Implemented using WIN 100-nm GaAs pHEMT technology,
this circuit achieves variable phase shifts through transmission lines
and diodes whose capacitance varies with voltage. A single-stage phase
shifter achieves a 60◦ phase shift, and a 3-stage con guration achieves
phase shifts above 180◦.
In Chapter 4, we investigate the design of a Q-band GaAs power
amplifi er. Using a single-stage common-source amplifi er architecture,
this circuit aims to test the process limits and validate design and simulation
methodologies through practical implementation. The ampli fier,
realized with WIN 100-nm GaAs pHEMT technology, features an 8-
nger transistor with a unit gate width (UGW) of 50 μm and layout
options of 4n and 8n. Impedance matching is achieved through transmission
lines to mitigate process variations and through lumped LC
components and transmission lines to minimize area. Additionally, RC
parallel networks are used at the transistor gates for stability within
the operating frequency band, and bypass capacitors are employed to
stabilize the circuit at low frequencies.
This study explores the design and performance optimization of
phase shifters and amplifi ers in Q-band phased array systems using
TSMC 90-nm CMOS and WIN 100-nm GaAs pHEMT technologies.
These components demonstrate excellent performance in high-frequency
applications, eectively enhancing signal gain and stability. | en_US |