Microwave CMOS VCOs and Front-Ends - using integrated passives on-chip and on-carrier

The increasing demand for high data rates in wireless communication systems is increasing the requirements on the transceiver front-ends, as they are pushed to utilize more and wider bands at higher frequencies. The work in this thesis is focused on receiver front-ends composed of Low Noise Amplifiers (LNAs), Mixers, and Voltage Controlled Oscillators (VCOs) operating at microwave frequencies. Traditionally, microwave electronics has used exclusive and more expensive semiconductor technologies (III-V materials). However, the rapid development of consumer electronics (e.g. video game consoles) the last decade has pushed the silicon CMOS IC technology towards even smaller feature sizes. This has resulted in high speed transistors (high fT and fmax) with low noise figures. However, as the breakdown voltages have decreased, a lower supply voltage must be used, which has had a negative impact on linearity and dynamic range. Nonetheless, todays downscaled CMOS technology is a feasible alternative for many microwave and even millimeter wave applications. The low quality factor (Q) of passive components on-chip usually limits the high frequency performance. For inductors realized in a standard CMOS process the substrate coupling results in a degraded Q. The quality factor can, however, be improved by moving the passive components off-chip and integrating them on a low loss carrier. This thesis therefore features microwave front-end and VCO designs in CMOS, where some designs have been flip-chip mounted on carriers featuring high Q inductors and low loss baluns. The thesis starts with an introduction to wireless communication, receiver architectures, front-end receiver blocks, and low loss carrier technology, followed by the included papers. The six included papers show the capability of CMOS and carrier technology at microwave frequencies: Papers II, III, and VI demonstrate fully integrated CMOS circuit designs. An LC-VCO using an accumulation mode varactor is presented in Paper II, a QVCO using 4-bit switched tuning is shown in Paper III, and a quadrature receiver front-end (including QVCO) is demonstrated in paper VI. Papers I and IV demonstrate receiver front-ends using low loss baluns on carrier for the LO and RF signals. Paper IV also includes a front-end using single-ended RF input which is converted to differential form in a novel merged LNA and balun. A VCO demonstrating the benefits of a high Q inductor on carrier is presented in Paper V

Innovative Design and Realization of Microwave and Millimeter-Wave Integrated circuits

Ph.DDOCTOR OF PHILOSOPH

Design of injection locked frequency divider in 65nm CMOS technology for mmW applications

In this paper, an Injection Locking Frequency Divider (ILFD) in 65 nm RF CMOS Technology for applications in millimeter-wave (mm-W) band is presented. The proposed circuit achieves 12.69% of locking range without any tuning mechanism and it can cover the entire mm-W band in presence of Process, Voltage and Temperature (PVT) variations by changing the Injection Locking Oscillator (ILO) voltage control. A design methodology flow is proposed for ILFD design and an overview regarding CMOS capabilities and opportunities for mm-W transceiver implementation is also exposed.Postprint (published version

Analysis and Design of a 1.8-GHz CMOS LC Quadrature VCO

This paper presents a quadrature voltage-controlled oscillator (QVCO) based on the coupling of two LC-tank VCOs. A simplified theoretical analysis for the oscillation frequency and phase noise displayed by the QVCO in the 1/f/sup 3/ region is developed, and good agreement is found between theory and simulation results. A prototype for the QVCO was implemented in a 0.35-/spl mu/m CMOS process with three standard metal layers. The QVCO could be tuned between 1.64 and 1.97 GHz, and showed a phase noise of -140 dBc/Hz or less across the tuning range at a 3-MHz offset frequency from the carrier, for a current consumption of 25 mA from a 2-V power supply. The equivalent phase error between I and Q signals was at most 0.25/spl deg/

USING VCOS AS RF MEASURING DEVICES

This thesis presents an alternative way to test the amount of energy harvested by an antenna. Accurately measuring the amount of energy an antenna harvests is a challenge. The test equipment that touches the antenna can greatly affect the results of the test. Using a VCO to measure an antenna's harvested power enables accuracy and prevents the need to attach testing equipment. The VCO is powered by a harvesting antenna. The frequency produced is then output to a transmitting antenna. The output frequency of the VCO can easily be determined and then used to look up the power from the characteristics of the VCO. A background study of types of VCOs, and VCOs available on the market will also be included in this thesis. Finally the experiment setups and results will be presented

Voltage controlled oscillator for mm-wave radio systems

Abstract. The advancement in silicon technology has accelerated the development of integrated millimeter-wave transceiver systems operating up to 100 GHz with sophisticated functionality at a reduced consumer cost. Due to the progress in the field of signal processing, frequency modulated continuous wave (FMCW) radar has become common in recent years. A high-performance local oscillator (LO) is required to generate reference signals utilized in these millimeter-wave radar transceivers. To accomplish this, novel design techniques in fundamental voltage controlled oscillators (VCO) are necessary to achieve low phase noise, wide frequency tuning range, and good power efficiency. Although integrated VCOs have been studied for decades, as we move higher in the radio frequency spectrum, there are new trade-offs in the performance parameters that require further characterization. The work described in this thesis aims to design a fully integrated fundamental VCO targeting to 150 GHz, i.e., D-Band. The purpose is to observe and analyze the design limitations at these high frequencies and their corresponding trade-offs during the design procedure. The topology selected for this study is the cross-coupled LC tank VCO. For the study, two design topologies were considered: a conventional cross-coupled LC tank VCO and an inductive divider cross-coupled LC tank VCO. The conventional LC tank VCO yields better performance in terms of phase noise and tuning range. It is observed that the VCO is highly sensitive to parasitic contributions by the transistors, and the layout interconnects, thus limiting the targeted frequency range. The dimensions of the LC tank and the transistors are selected carefully. Moreover, the VCO performance is limited by the low Q factor of the LC tank governed by the varactor that is degrading the phase noise performance and the tuning range, respectively. The output buffer loaded capacitance and the core power consumption of the VCO are optimized. The layout is drawn carefully with strategies to minimize the parasitic effects. Considering all the design challenges, a 126 GHz VCO with a tuning range of 3.9% is designed. It achieves FOMT (Figure-of-merit) of -172 dBc/Hz, and phase noise of -99.14 dBc/Hz at 10 MHz offset, Core power consumption is 8.9 mW from a 1.2 V supply. Just falling short of the targeted frequency, the design is suitable for FMCW radar applications for future technologies. The design was done using Silicon-on-Insulator (SOI) CMOS technology

Investigation on LIGA-MEMS and on-chip CMOS capacitors for a VCO application

Modern communication systems require high performance radio frequency (RF) and microwave circuits and devices. This is becoming increasingly challenging to realize in the content of cost/size constraints. Integrated circuits (ICs) satisfy the cost/size requirement, but performance is often sacri¯ced. For instance, high quality factor (Q factor) passive components are difficult to achieve in standard silicon-based IC processes.In recent years, microelectromechanical systems (MEMS) devices have been receiving increasing attention as a possible replacement for various on-chip passive elements, offering potential improvement in performance while maintaining high levels of integration. Variable capacitors (varactor) are common elements used in various applications. One of the MEMS variable capacitors that has been recently developed is built using deep X-ray lithography (as part of the LIGA process). This type of capacitor exhibits high quality factor at microwave frequencies.The complementary metal oxide semiconductor (CMOS) technology dominates the silicon IC process. CMOS becomes increasingly popular for RF applications due to its advantages in level of integration, cost and power consumption. This research demonstrates a CMOS voltage-controlled oscillator (VCO) design which is used to investigate methods, advantages and problems in integrating LIGA-MEMS devices to CMOS RF circuits, and to evaluate the performance of the LIGA-MEMS variable capacitor in comparison with the conventional on-chip CMOS varactor. The VCO was designed and fabricated using TSMC 0.18 micron CMOS technology. The core of the VCO, including transistors, resistors, and on-chip inductors was designed to connect to either an on-chip CMOS varactor or an off-chip LIGA-MEMS capacitor to oscillate between 2.6 GHz and 2.7 GHz. Oscillator phase noise analysis is used to compare the performance between the two capacitors. The fabricated VCO occupied an area of 1 mm^2.This initial attempt at VCO fabrication did not produce a functional VCO, so the performance of the capacitors with the fabricated VCO could not be tested. However, the simulation results show that with this LIGA-MEMS capacitor, a 6.4 dB of phase noise improvement at 300 kHz offset from the carrier is possible in a CMOS-based VCO design