A Quadrature Frequency Generation Chain for Direct-conversion Phased-array 5G Transceivers

Abstract

The 5th generation (5G) has recently specified a new spectrum range, FR2- 5G
New Radio (5G-NR), to provide higher spectral efficiency and channel capacity
for ubiquitous cellular connectivity where the user ends can be in various types
such as picocell stations, sensor nodes, cloud servers, hand-held devices, and so
on. Due to the advantage of phased array antennas in performing beam-forming,
and improving SNR at higher spectra, multi-antenna systems have gained an inevitable role in developing such radios. However, attributed to their multi-path
feature, their corresponding silicon solutions are often complex, power-hungry, and
bulky which all together limit their practicality for low power and compact solutions. This introduces an additional hurdle to the RFIC units of 5G radios which already is challenged by strict cellular requirements.
During the recent years, the developing short channel silicon-on-insulator (SOI)
CMOS technology has provided distinguished characteristics for CMOS transistors.
Thanks to the smaller scale and the isolated substrate, the CMOS transistors
provide a considerable improvement in power efficiency. Also, they provide
a highly controllable characteristic promising novel architectures and circuits. All the merits considered, short channel SOI technology has taken an indisputable role in developing advanced RFIC units.
This thesis benefits from Global Foundries’ 22-nm fully depleted silicon-on-insulator (FD-SOI) process, and presents a power-efficient LO phase shifting RFIC unit for direct conversion phased array transceivers. The proposed solution covers the sub- 30 GHz bands including n257, n258, and n261 (24.25 GHz- 29.5 GHz). The chain supports the required frequency range with a single VCO by providing a 31.5%
tuning range. The VCO occupies 0.025 mm2, and consumes 5.1 mW on average and its phase noise at 1 MHz offset varies between -95 dBc/Hz to -98 dBc/Hz. Accordingly, its FOM and FOMt at 1 MHz offset is -177.8 dBc/Hz and -187.7 dBc/Hz respectively. Furthermore, the chain provides a tunable quadrature LO generation that consumes 15.8 mW and provides at least 40 dBc image rejection ratio (IRR) over the targeted bandwidth. As the last stage, for accomplishing the array steering, a low power active phase shifting unit is proposed. The proposed phase shifter occupies 0.01 mm2, and provides 93-110 degree phase-shifting for each of the quadrants within the specified bandwidth. The phase-shifting unit and its following output buffer consume 2.8 mW and 2.7 mW respectively For each quadrature paths.

Popular Abstract

The ever increasing demand for ubiquitous wireless connectivity has pushed the providing networks to a new level of evolution. The vast diversity of user-ends with various applications, has urged the demands to grow in different aspects. For example, in developing smart cities, by increasing the number of monitoring sensors, the network needs to provide higher channel capacity to ensure their connectivity. In the virtual reality devices, the network requires to provide higher data rate and lower latency, and in the cloud-based AI applications which have a significant role in eliminating power-hungry on-device AI processors, a very reliable and low latency connection is demanded. In a dynamic wireless environment, a single network must be capable to handle all these criteria.
The 5th generation (5G) has recently specified a new spectrum range, FR2- 5GNew Radio (5G-NR) to respond to the aforementioned demands by providing new channels with wider bandwidths and various carrier aggregation possibilities. The 5G network is capable of providing over 10 Gbps peak data rate, less than 1ms latency, over 99.999 % reliability, and zero mobility interruption time.
Since the lower frequencies are already occupied by other standards, the new bands are placed in higher spectra ranging from 24 GHz to 52 GHz. Attributed to the nature of electromagnetic waves, providing a high SNR requires a novel antenna front-ends called phased-array antennas. Such antennas have shown a successful figure in providing high SNR and selectivity. However, their RFIC units are often bulky, and power-hungry.
This thesis benefits from state-of-the-art 22nm FD-SOI CMOS technology by Global Foundries, and has investigated novel ways to benefit from advantages of advanced technology to reduce the form factor and power consumption of phased-array RFIC radios. In this regard, an LO phase-shifting chain for sub-30 GHz bands including n257, n258, and n261 (24.25 GHz- 29.5 GHz) are proposed. The chain supports the required frequency range with a single VCO by providing a 31.5%tuning range. The VCO occupies 0.025 mm2 and consumes 5.1 mW on average and its phase noise at 1 MHz offset varies between -95 dBc/Hz to -98 dBc/Hz. Accordingly, its FOM and FOMt at 1 MHz offset is -177.8 dBc/Hz and -187.7dBc/Hz respectively. Furthermore, the chain provides a tunable quadrature LO generation that consumes 15.8 mW and provides at least 40 dBc image rejection ratio (IRR) over the targeted bandwidth. As the last stage, for accomplishing the array steering, a low power active phase shifting unit is proposed. The proposed phase shifter occupies 0.01mm2, and provides 93-110 degree phase-shifting for each of the quadrants within the specified bandwidth. The phase-shifting unit and its following output buffer consume 2.8 mW and 2.7 mW respectively For each quadrature paths.

• author: Yadegar Amin, Hamid
• supervisor: Markus Törmänen
• organization: Department of Electrical and Information Technology
• course: EITM02 20192
• year: 2020
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: 5G Phased array mm-wave FR2
• report number: LU/LTH-EIT 2020-756
• language: English
• id: 9025320
• date added to LUP: 2020-08-10 15:06:48
• date last changed: 2020-08-10 15:06:48