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CMOS Signal Synthesizers for Emerging RF-to-Optical Applications
The need for clean and powerful signal generation is ubiquitous, with applications spanning the spectrum from RF to mm-Wave, to into and beyond the terahertz-gap. RF applications including mobile telephony and microprocessors have effectively harnessed mixed-signal integration in CMOS to realize robust on-chip signal sources calibrated against adverse ambient conditions. Combined with low cost and high yield, the CMOS component of hand-held devices costs a few cents per part per million parts. This low cost, and integrated digital processing, make CMOS an attractive option for applications like high-resolution imaging and ranging, and the emerging 5-G communication space. RADAR techniques when expanded to optical frequencies can enable micrometers of resolution for 3D imaging. These applications, however, impose upto 100x more exacting specifications on power and spectral purity at much higher frequencies than conventional RF synthesizers.
This generation of applications will present unconventional challenges for transistor technologies - whether it is to squeeze performance in the conventionally used spectrum, already wrung dry, or signal generation and system design in the relatively emptier mm-Wave to sub-mmWave spectrum, much of the latter falling in the ``Terahertz Gap". Indeed, transistor scaling and innovative device physics leading to new transistor topologies have yielded higher cut-off frequencies in CMOS, though still lagging well behind SiGe and III-V semiconductors. To avoid multimodule solutions with functionality partitioned across different technologies, CMOS must be pushed out of its comfort zone, and technology scaling has to have accompanying breakthroughs in design approaches not only at the system but also at the block level. In this thesis, while not targeting a specific application, we seek to formulate the obstacles in synthesizing high frequency, high power and low noise signals in CMOS and construct a coherent design methodology to address them. Based on this, three novel prototypes to overcome the limiting factors in each case are presented.
The first half of this thesis deals with high frequency signal synthesis and power generation in CMOS. Outside the range of frequencies where the transistor has gain, frequency generation necessitates harmonic extraction either as harmonic oscillators or as frequency multipliers. We augment the traditional maximum oscillation frequency metric (fmax), which only accounts for transistor losses, with passive component loss to derive an effective fmax metric. We then present a methodology for building oscillators at this fmax, the Maximum Gain Ring Oscillator. Next, we explore generating large signals beyond fmax through harmonic extraction in multipliers. Applying concepts of waveform shaping, we demonstrate a Power Mixer that engineers transistor nonlinearity by manipulating the amplitudes and relative phase shifts of different device nodes to maximize performance at a specific harmonic beyond device cut-off.
The second half proposes a new architecture for an ultra-low noise phase-locked loop (PLL), the Reference-Sampling PLL. In conventional PLLs, a noisy buffer converts the slow, low-noise sine-wave reference signal to a jittery square-wave clock against which the phase of a noisy voltage-controlled oscillator (VCO) is corrected. We eliminate this reference buffer, and measure phase error by sampling the reference sine-wave with the 50x faster VCO waveform already available on chip, and selecting the relevant sample with voltage proportional to phase error. By avoiding the N-squared multiplication of the high-power reference buffer noise, and directly using voltage-mode phase error to control the VCO, we eliminate several noisy components in the controlling loop for ultra-low integrated jitter for a given power consumption. Further, isolation of the VCO tank from any varying load, unlike other contemporary divider-less PLL architectures, results in an architecture with record performance in the low-noise and low-spur space.
We conclude with work that brings together concepts developed for clean, high-power signal generation towards a hybrid CMOS-Optical approach to Frequency-Modulated Continuous-Wave (FMCW) Light-Detection-And-Ranging (LIDAR). Cost-effective tunable lasers are temperature-sensitive and have nonlinear tuning profiles, rendering precise frequency modulations or 'chirps' untenable. Locking them to an electronic reference through an electro-optic PLL, and electronically calibrating the control signal for nonlinearity and ambient sensitivity, can make such chirps possible. Approaches that build on the body of advances in electrical PLLs to control the performance, and ease the specification on the design of optical systems are proposed. Eventually, we seek to leverage the twin advantages of silicon-intensive integration and low-cost high-yield towards developing a single-chip solution that uses on-chip signal processing and phased arrays to generate precise and robust chirps for an electronically-steerable fine LIDAR beam
Saw-Less radio receivers in CMOS
Smartphones play an essential role in our daily life. Connected to the internet, we can easily keep in touch with family and friends, even if far away, while ever more apps serve us in numerous ways. To support all of this, higher data rates are needed for ever more wireless users, leading to a very crowded radio frequency spectrum. To achieve high spectrum efficiency while reducing unwanted interference, high-quality band-pass filters are needed. Piezo-electrical Surface Acoustic Wave (SAW) filters are conventionally used for this purpose, but such filters need a dedicated design for each new band, are relatively bulky and also costly compared to integrated circuit chips. Instead, we would like to integrate the filters as part of the entire wireless transceiver with digital smartphone hardware on CMOS chips. The research described in this thesis targets this goal. It has recently been shown that N-path filters based on passive switched-RC circuits can realize high-quality band-select filters on CMOS chips, where the center frequency of the filter is widely tunable by the switching-frequency. As CMOS downscaling following Mooreโs law brings us lower clock-switching power, lower switch on-resistance and more compact metal-to-metal capacitors, N-path filters look promising. This thesis targets SAW-less wireless receiver design, exploiting N-path filters. As SAW-filters are extremely linear and selective, it is very challenging to approximate this performance with CMOS N-path filters. The research in this thesis proposes and explores several techniques for extending the linearity and enhancing the selectivity of N-path switched-RC filters and mixers, and explores their application in CMOS receiver chip designs. First the state-of-the-art in N-path filters and mixer-first receivers is reviewed. The requirements on the main receiver path are examined in case SAW-filters are removed or replaced by wideband circulators. The feasibility of a SAW-less Frequency Division Duplex (FDD) radio receiver is explored, targeting extreme linearity and compression Irequirements. A bottom-plate mixing technique with switch sharing is proposed. It improves linearity by keeping both the gate-source and gate-drain voltage swing of the MOSFET-switches rather constant, while halving the switch resistance to reduce voltage swings. A new N-path switch-RC filter stage with floating capacitors and bottom-plate mixer-switches is proposed to achieve very high linearity and a second-order voltage-domain RF-bandpass filter around the LO frequency. Extra out-of-band (OOB) rejection is implemented combined with V-I conversion and zero-IF frequency down-conversion in a second cross-coupled switch-RC N-path stage. It offers a low-ohmic high-linearity current path for out-of-band interferers. A prototype chip fabricated in a 28 nm CMOS technology achieves an in-band IIP3 of +10 dBm , IIP2 of +42 dBm, out-of-band IIP3 of +44 dBm, IIP2 of +90 dBm and blocker 1-dB gain-compression point of +13 dBm for a blocker frequency offset of 80 MHz. At this offset frequency, the measured desensitization is only 0.6 dB for a 0-dBm blocker, and 3.5 dB for a 10-dBm blocker at 0.7 GHz operating frequency (i.e. 6 and 9 dB blocker noise figure). The chip consumes 38-96 mW for operating frequencies of 0.1-2 GHz and occupies an active area of 0.49 mm2. Next, targeting to cover all frequency bands up to 6 GHz and achieving a noise figure lower than 3 dB, a mixer-first receiver with enhanced selectivity and high dynamic range is proposed. Capacitive negative feedback across the baseband amplifier serves as a blocker bypassing path, while an extra capacitive positive feedback path offers further blocker rejection. This combination of feedback paths synthesizes a complex pole pair at the input of the baseband amplifier, which is up-converted to the RF port to obtain steeper RF-bandpass filter roll-off than the conventional up-converted real pole and reduced distortion. This thesis explains the circuit principle and analyzes receiver performance. A prototype chip fabricated in 45 nm Partially Depleted Silicon on Insulator (PDSOI) technology achieves high linearity (in-band IIP3 of +3 dBm, IIP2 of +56 dBm, out-of-band IIP3 = +39 dBm, IIP2 = +88 dB) combined with sub-3 dB noise figure. Desensitization due to a 0-dBm blocker is only 2.2 dB at 1.4 GHz operating frequency. IIFinally, to demonstrate the performance of the implemented blocker-tolerant receiver chip designs, a test setup with a real mobile phone is built to verify the sensitivity of the receiver chip for different practical blocking scenarios
Design and Implementation of a LowโPower Wireless Respiration Monitoring Sensor
Wireless devices for monitoring of respiration activities can play a major role in advancing modern home-based health care applications. Existing methods for respiration monitoring require special algorithms and high precision filters to eliminate noise and other motion artifacts. These necessitate additional power consuming circuitry for further signal conditioning. This dissertation is particularly focused on a novel approach of respiration monitoring based on a PVDF-based pyroelectric transducer. Low-power, low-noise, and fully integrated charge amplifiers are designed to serve as the front-end amplifier of the sensor to efficiently convert the charge generated by the transducer into a proportional voltage signal. To transmit the respiration data wirelessly, a lowpower transmitter design is crucial. This energy constraint motivates the exploration of the design of a duty-cycled transmitter, where the radio is designed to be turned off most of the time and turned on only for a short duration of time. Due to its inherent duty-cycled nature, impulse radio ultra-wideband (IR-UWB) transmitter is an ideal candidate for the implementation of a duty-cycled radio. To achieve better energy efficiency and longer battery lifetime a low-power low-complexity OOK (on-off keying) based impulse radio ultra-wideband (IR-UWB) transmitter is designed and implemented using standard CMOS process. Initial simulation and test results exhibit a promising advancement towards the development of an energy-efficient wireless sensor for monitoring of respiration activities
Flexible Receivers in CMOS for Wireless Communication
Consumers are pushing for higher data rates to support more services that are introduced in mobile applications. As an example, a few years ago video-on-demand was only accessed through landlines, but today wireless devices are frequently used to stream video. To support this, more flexible network solutions have merged in 4G, introducing new technical problems to the mobile terminal. New techniques are thus needed, and this dissertation explores five different ideas for receiver front-ends, that are cost-efficient and flexible both in performance and operating frequency. All ideas have been implemented in chips fabricated in 65 nm CMOS technology and verified by measurements. Paper I explores a voltage-mode receiver front-end where sub-threshold positive feedback transistors are introduced to increase the linearity in combination with a bootstrapped passive mixer. Paper II builds on the idea of 8-phase harmonic rejection, but simplifies it to a 6-phase solution that can reject noise and interferers at the 3rd order harmonic of the local oscillator frequency. This provides a good trade-off between the traditional quadrature mixer and the 8- phase harmonic rejection mixer. Furthermore, a very compact inductor-less low noise amplifier is introduced. Paper III investigates the use of global negative feedback in a receiver front-end, and also introduces an auxiliary path that can cancel noise from the main path. In paper IV, another global feedback based receiver front-end is designed, but with positive feedback instead of negative. By introducing global positive feedback, the resistance of the transistors in a passive mixer-first receiver front-end can be reduced to achieve a lower noise figure, while still maintaining input matching. Finally, paper V introduces a full receiver chain with a single-ended to differential LNA, current-mode downconversion mixers, and a baseband circuity that merges the functionalities of the transimpedance amplifier, channel-select filter, and analog-to-digital converter into one single power-efficient block
Integrated Circuit Design for Radiation Sensing and Hardening.
Beyond the 1950s, integrated circuits have been widely used in a number of electronic devices surrounding peopleโs lives. In addition to computing electronics, scientific and medical equipment have also been undergone a metamorphosis, especially in radiation related fields where compact and precision radiation detection systems for nuclear power plants, positron emission tomography (PET), and radiation hardened by design (RHBD) circuits for space applications fabricated in advanced manufacturing technologies are exposed to the non-negligible probability of soft errors by radiation impact events. The integrated circuit design for radiation measurement equipment not only leads to numerous advantages on size and power consumption, but also raises many challenges regarding the speed and noise to replace conventional design modalities. This thesis presents solutions to front-end receiver designs for radiation sensors as well as an error detection and correction method to microprocessor designs under the condition of soft error occurrence.
For the first preamplifier design, a novel technique that enhances the bandwidth and suppresses the input current noise by using two inductors is discussed. With the dual-inductor TIA signal processing configuration, one can reduce the fabrication cost, the area overhead, and the power consumption in a fast readout package. The second front-end receiver is a novel detector capacitance compensation technique by using the Miller effect. The fabricated CSA exhibits minimal variation in the pulse shape as the detector capacitance is increased. Lastly, a modified D flip-flop is discussed that is called Razor-Lite using charge-sharing at internal nodes to provide a compact EDAC design for modern well-balanced processors and RHBD against soft errors by SEE.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111548/1/iykwon_1.pd
Low-Power Wake-Up Receivers
The Internet of Things (IoT) is leading the world to the Internet of Everything (IoE), where things, people, intelligent machines, data and processes will be connected together. The key to enter the era of the IoE lies in enormous sensor nodes being deployed in the massively expanding wireless sensor networks (WSNs). By the year of 2025, more than 42 billion IoT devices will be connected to the Internet. While the future IoE will bring priceless advantages for the life of mankind, one challenge limiting the nowadays IoT from further development is the ongoing power demand with the dramatically growing number of the wireless sensor nodes.
To address the power consumption issue, this dissertation is motivated to investigate low-power wake-up receivers (WuRXs) which will significantly enhance the sustainability of the WSNs and the environmental awareness of the IoT.
Two proof-of-concept low-power WuRXs with focuses on two different application scenarios have been proposed. The first WuRX, implemented in a cost-effective 180-nm CMOS semiconductor technology, operates at 401โ406-MHz band. It is a good candidate for application scenarios, where both a high sensitivity and an ultra-low power consumption are in demand. Concrete use cases are, for instance, medical implantable applications or long-range communications in rural areas. This WuRX does not rely on a further assisting semiconductor technology, such as MEMS which is widely used in state-of-the-art WuRXs operating at similar frequencies. Thus, this WuRX is a promising solution to low-power low-cost IoT. The second WuRX, implemented in a 45-nm RFSOI CMOS technology, was researched for short-range communication applications, where high-density conventional IoT devices should be installed. By investigation of the WuRX for operation at higher frequency band from 5.5 GHz to 7.5 GHz, the nowadays ever more over-traffic issues that arise at low frequency bands such as 2.4 GHz can be substantially addressed.
A systematic, analytical research route has been carried out in realization of the proposed WuRXs. The thesis begins with a thorough study of state-of-the-art WuRX architectures. By examining pros and cons of these architectures, two novel architectures are proposed for the WuRXs in accordance with their specific use cases. Thereon, key WuRX parameters are systematically analyzed and optimized; the performance of relevant circuits is modeled and simulated extensively. The knowledge gained through these investigations builds up a solid theoretical basis for the ongoing WuRX designs. Thereafter, the two WuRXs have been analytically researched, developed and optimized to achieve their highest performance.
Proof-of-concept circuits for both the WuRXs have been fabricated and comprehensively characterized under laboratory conditions. Finally, measurement results have verified the feasibility of the design concept and the feasibility of both the WuRXs
๋ฉ๋ชจ๋ฆฌ ์ธํฐํ์ด์ค๋ฅผ ์ํ 4 ๋ ๋ฒจ ํ์ค ์งํญ ๋ณ์กฐ ์ฟผํฐ ๋ ์ดํธ ์์ ๊ธฐ ์ค๊ณ
ํ์๋
ผ๋ฌธ(๋ฐ์ฌ) -- ์์ธ๋ํ๊ต๋ํ์ : ๊ณต๊ณผ๋ํ ์ ๊ธฐยท์ ๋ณด๊ณตํ๋ถ, 2022. 8. ๊น์ํ.๋ณธ ์ฐ๊ตฌ์์๋ ๋ฉ๋ชจ๋ฆฌ ์ธํฐํ์ด์ค๋ฅผ ์ํ 4 ๋ ๋ฒจ ํ์ค ์งํญ ๋ณ์กฐ (PAM-4) ์์ ๊ธฐ์ ์ง๊ต ํด๋ก์ ์์ฑํ๋ ์ง๊ต ์ ํธ ๋ณด์ ๊ธฐ๋ฅผ ์ ์๋๋ค. ๋ฐ์ดํฐ ์ผํฐ์์ ์ฆ๊ฐํ๋ IP ํธ๋ํฝ์ ๊ณ ์ ๋ฐ ์ ์ ๋ ฅ ๋ฉ๋ชจ๋ฆฌ ์ธํฐํ์ด์ค์ ๋ํ ์์๋ฅผ ์ฆ๊ฐ์์ผ์๋ค. ์ด๋ฌํ ์๊ตฌ๋ฅผ ๋ง์กฑ์ํค๊ธฐ ์ํด ํด๋ญ ๋ฐ ๋์ดํด์คํธ ์ฃผํ์๋ฅผ ๋์ด์ง ์๊ณ ๋ ๋ฐ์ดํฐ ์ ์ก๋ฅ ์ ๋์ผ ์ ์๋ PAM-4 ์ ํธ๊ฐ ์ฃผ๋ชฉ์ ๋ฐ๊ณ ์๋ค.
PAM-4 ์ ํธ๋ ์ ๋ก ๋น ๋ณต๊ท ์ ํธ (NRZ) ๋ณด๋ค 3๋ฐฐ ๋ฎ์ ์์ง ๋ง์ง์ ๊ฐ์ง๋ฉฐ, ์ด๋ ๊ฒฐ์ ํผ๋๋ฐฑ ์ดํ๋ผ์ด์ ๋ด ์ฌ๋ผ์ด์ค์ ํด๋ญ-ํ ๋๋ ์ด๋ฅผ ์ฆ๊ฐ์ํค๋ฉฐ, ์ด๋ก ์ธํด PAM-4 ๊ฒฐ์ ํผ๋๋ฐฑ ์ดํ๋ผ์ด์ ์ ์ฑ๋ฅ์ ์ ํํ๋ ์์ธ์ด๋ค.
๋ณธ ์ฐ๊ตฌ์์๋ ์ธ๋ฒํฐ ๊ธฐ๋ฐ์ ํฉ์ฐ๊ธฐ๋ฅผ ์ด์ฉ, ์ ํ์ ์ผ๋ก ์ ํธ๋ฅผ ์ฆํญ์ํค๋ ๊ฒฐ์ ํผ๋๋ฐฑ ์ดํ๋ผ์ด์ ๋ฅผ ์ฌ์ฉํจ์ผ๋ก์จ ์ฌ๋ผ์ด์์ ์ ๋ ฅ ์๋ชจ๋ฅผ ์ฆ๊ฐ์ํค์ง ์์ผ๋ฉด์ ์ฌ๋ผ์ด์์ ํด๋ญ-ํ ๋๋ ์ด๋ฅผ ์ค์ผ ์ ์๋ค.
๋ํ, ์ ์ํ ์ง์ฐ ์ด๋ ์ปจํธ๋กค๋ฌ๋ฅผ ํฌํจํ๋ ์ง๊ต ์ ํธ ๋ณด์ ๊ธฐ๋ ๋์ ์ ํ๋์ ๋น ๋ฅธ ์คํ ๋ณด์ ์ผ๋ก ์ฟผ๋๋ฌ์ฒ ํด๋ญ ๊ฐ์ ์คํ๋ฅผ ๊ต์ ํ ์ ์๋ค.
์ ํ์ ๋ ์ฆํญ ๊ฒฐ์ ํผ๋๋ฐฑ ์ดํ๋ผ์ด์ ์ ์ ์ํ ์ง์ฐ ์ด๋ ์ปจํธ๋กค๋ฌ๋ฅผ ํฌํจํ๋ ์ง๊ต ์ ํธ ๋ณด์ ๊ธฐ์ ์ฑ๋ฅ์ ๊ฒ์ฆํ๊ธฐ ์ํด ํ๋กํ ํ์
์นฉ์ ์ ์ํ์๋ค. ์ ์๋ ์นฉ์ 65 nm CMOS ๊ณต์ ์ผ๋ก ์ ์๋์๋ค. ํ๋กํ ํ์
์นฉ์ 24 Gb/s/pin ์์ 10-12 ์ ๋นํธ ์๋ฌ์จ์ 100 mUI ์ ์ ํธ ๋๋น๋ก ๋ฌ์ฑํ์๋ค. ํ๋กํ ํ์
์นฉ ๋ด PAM-4 ์์ ๊ธฐ๋ 0.73 pJ/b ์ ์๋์ง ํจ์จ์ ๊ฐ๋๋ค.
๋ํ ์ ์ํ ์ง์ฐ ์ด๋ ์ปจํธ๋กค๋ฌ๋ฅผ ํฌํจํ๋ ์ง๊ต ์ ํธ ๋ณด์ ๊ธฐ๋ 3 GHz ์ฟผ๋๋ฌ์ฒ ํด๋ญ ๊ฐ ์ต๋ 21.2 ps ์ ์คํ๋ฅผ 0.8 ps ๊น์ง ์ค์ผ ์ ์์ผ๋ฉฐ, ์ด ๋ 76.9 ns ์ ๊ต์ ์๊ฐ์ ๊ฐ๋๋ค. ์ ์ํ๋ ์ง๊ต ์ ํธ ๋ณด์ ๊ธฐ๋ 3 GHz ์์ 2.15 mW/GHz ์ ์ ๋ ฅ ํจ์จ์ ๊ฐ๋๋ค.A four-level pulse amplitude modulation (PAM-4) receiver, and a quadrature signal corrector (QSC) that generates quadrature clocks for memory interfaces is presented. Increasing IP traffic in data centers has increased the demand for high-speed and low-power memory interfaces. To satisfy this demand, PAM-4 signaling, which can increase data-rate without increasing clock and Nyquist frequency, is received considerable attention.
PAM- signaling has vertical which three times lower than non-return-to-zero (NRZ) signaling, which makes the clock-to-Q delay of the slicer in the decision feedback equalizer (DFE) increases. This makes the DFE difficult to satisfy the timing constraint. In this paper, by using a DFE with inverter-based summers, the clock-to-Q delay of the slicer can be reduced without increasing the power consumption of the slicers.
Also, the QSC using an adaptive delay gain controller can correct the skew between the quadrature clock with low skew and short correction time.
The prototype receiver including the DFE with the inverter-based summer and the QSC using the adaptive delay gain controller was fabricated in 65 nm CMOS process. The prototype chip can achieve a bit error rate (BER) of 10-12 at 24 Gb/s/pin, and at this time, an eye width of 100 mUI is secured. The efficiency of the receiver is 0.73 pJ/b. In addition, the QSC cna reduce the maximum 21.2 ps of skew between 3 GHz quadrature clocks to 0.8 ps and has a correction time of 76.9 ns. The efficiency of the QSC is 2.15 mW/GHz.ABSTRACT 1
CONTENTS 3
LIST OF FIGURES 5
LIST OF TABLE 9
CHAPTER 1 1
INTRODUCTION 1
1.1 MOTIVATION 1
1.2 PAM-4 SIGNALING 7
1.2.1 DESIGN CONSIDERATIONS ON PAM-4 RECEIVER 10
1.2.2 PRIOR WORKS 14
1.3 QUARTER-RATE ARCHITECTURE 18
1.3.1 DESIGN CONSIDERATION ON QUARTER-RATE ARCHITECTURE 20
1.3.2 PRIOR WORKS 25
1.4 SUMMARY 28
1.5 THESIS ORGANIZATION 30
CHAPTER 2 31
CONCEPTS OF DFE WITH INVERTER-BASED SUMMER 31
2.1 CONCEPTUAL ARCHITECTURE OF DFE WITH INVERTER-BASED SUMMER 32
2.2 DESIGN CONSIDERATION OF INVERTER-BASED SUMMER 37
CHAPTER 3 41
CONCEPTS OF QUADRATURE SIGNAL CORRECTOR USING ADAPTIVE DELAY GAIN CONTROLLER 41
3.1 OPERATION OF PROPOSED QUADRATURE SIGNAL CORRECTOR 42
3.2 LOOP FILTER INCLUDING ADAPTIVE DELAY GAIN CONTROLLER 45
CHAPTER 4 48
ARCHITECTURE AND IMPLEMENTATION 48
4.1 OVERALL ARCHITECTURE 49
4.2 ANALOG FRONT END 52
4.3 DECISION FEEDBACK EQUALIZER WITH INVERTER-BASED SUMMER 54
4.4 CLOCK PATH 62
4.5 QUADRATURE SIGNAL CORRECTOR WITH ADAPTIVE DELAY GAIN CONTROLLER 63
CHAPTER 5 70
EXPERIMENTAL RESULTS 70
5.1 EXPERIMENTAL SETUP 70
5.2 EXPERIMENTAL RESULTS 74
5.2.1 MEASUREMENT RESULTS OF PAM-4 RECEIVER WITH DECISION FEEDBACK EQUALIZER USING INVERTER-BASED SUMMER 74
5.2.2 MEASUREMENT RESULTS OF QUADRATURE SIGNAL CORRECTOR USING ADAPTIVE DELAY GAIN CONTROLLER 77
CHAPTER 6 83
CONCLUSION 83
BIBLIOGRAPHY 86๋ฐ
Millimeter-Precision Laser Rangefinder Using a Low-Cost Photon Counter
In this book we successfully demonstrate a millimeter-precision laser rangefinder using a low-cost photon counter. An application-specific integrated circuit (ASIC) comprises timing circuitry and single-photon avalanche diodes (SPADs) as the photodetectors. For the timing circuitry, a novel binning architecture for sampling the received signal is proposed which mitigates non-idealities that are inherent to a system with SPADs and timing circuitry in one chip
Sub-Picosecond Jitter Clock Generation for Time Interleaved Analog to Digital Converter
Nowadays, Multi-GHz analog-to-digital converters (ADCs) are becoming more and more popular in radar systems, software-defined radio (SDR) and wideband communications, because they can realize much higher operation speed through using many interleaved sub-ADCs to relax ADC sampling rates. Although the time interleaved ADC has some issues such as gain mismatch, offset mismatch and timing skew between each ADC channel, these deterministic errors can be solved by previous works such as digital calibration technique. However, time-interleaved ADCs require a precise sample clock to achieve an acceptable effective-numberof-bits (ENOB) which can be degraded by jitter in the sample clock. The clock generation circuits presented in this work achieves sub-picosecond jitter performance in 180nm CMOS which is suitable for time-interleaved ADC. Two different test chips were fabricated in 180nm CMOS to investigate the low jitter design technique. The low jitter delay line in two chips were designed in two different ways, but both of them utilized the low jitter design technique. In first test chip, the measured RMS jitter is 0.1061ps for each delay stage. The second chip uses the proposed low jitter Delay-Locked Loop can work from 80MHz to 120MHz, which means it can provide the time interleaved ADC with 2.4GHz to 3.6GHz low jitter sample clock, the measured delay stage jitter performance in second test chip is 0.1085ps
Wireless wire - ultra-low-power and high-data-rate wireless communication systems
With the rapid development of communication technologies, wireless personal-area communication systems gain momentum and become increasingly important. When the market gets gradually saturated and the technology becomes much more mature, new demands on higher throughput push the wireless communication further into the high-frequency and high-data-rate direction. For example, in the IEEE 802.15.3c standard, a 60-GHz physical layer is specified, which occupies the unlicensed 57 to 64 GHz band and supports gigabit links for applications such as wireless downloading and data streaming. Along with the progress, however, both wireless protocols and physical systems and devices start to become very complex. Due to the limited cut-off frequency of the technology and high parasitic and noise levels at high frequency bands, the power consumption of these systems, especially of the RF front-ends, increases significantly. The reason behind this is that RF performance does not scale with technology at the same rate as digital baseband circuits. Based on the challenges encountered, the wireless-wire system is proposed for the millimeter wave high-data-rate communication. In this system, beamsteering directional communication front-ends are used, which confine the RF power within a narrow beam and increase the level of the equivalent isotropic radiation power by a factor equal to the number of antenna elements. Since extra gain is obtained from the antenna beamsteering, less front-end gain is required, which will reduce the power consumption accordingly. Besides, the narrow beam also reduces the interference level to other nodes. In order to minimize the system average power consumption, an ultra-low power asynchronous duty-cycled wake-up receiver is added to listen to the channel and control the communication modes. The main receiver is switched on by the wake-up receiver only when the communication is identified while in other cases it will always be in sleep mode with virtually no power consumed. Before transmitting the payload, the event-triggered transmitter will send a wake-up beacon to the wake-up receiver. As long as the wake-up beacon is longer than one cycle of the wake-up receiver, it can be captured and identified. Furthermore, by adopting a frequency-sweeping injection locking oscillator, the wake-up receiver is able to achieve good sensitivity, low latency and wide bandwidth simultaneously. In this way, high-data-rate communication can be achieved with ultra-low average power consumption. System power optimization is achieved by optimizing the antenna number, data rate, modulation scheme, transceiver architecture, and transceiver circuitries with regards to particular application scenarios. Cross-layer power optimization is performed as well. In order to verify the most critical elements of this new approach, a W-band injection-locked oscillator and the wake-up receiver have been designed and implemented in standard TSMC 65-nm CMOS technology. It can be seen from the measurement results that the wake-up receiver is able to achieve about -60 dBm sensitivity, 10 mW peak power consumption and 8.5 ยตs worst-case latency simultaneously. When applying a duty-cycling scheme, the average power of the wake-up receiver becomes lower than 10 ยตW if the event frequency is 1000 times/day, which matches battery-based or energy harvesting-based wireless applications. A 4-path phased-array main receiver is simulated working with 1 Gbps data rate and on-off-keying modulation. The average power consumption is 10 ยตW with 10 Gb communication data per day
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