A Multi-Mode ULP Receiver Based on an Injection-Locked Oscillator for IoT Applications

This paper presents an ultra-low-power receiver based on the injection-locked oscillator (ILO), which is compatible with multiple modulation schemes such as on-off keying (OOK), binary frequency-shift keying (BFSK), and differential binary phase-shift keying (DBPSK). The receiver has been fabricated in 0.18-μm CMOS technology and operates in the ISM band of 2.4 GHz. A simple envelope detection can be used even for the demodulation of BFSK and DBPSK signals due to the conversion capability of the ILO from the frequency and phase to the amplitude. In the proposed receiver, a Q-enhanced single-ended-to-differential amplifier is employed to provide high-gain amplification as well as narrow band-pass filtering, which improves the sensitivity and selectivity of the receiver. In addition, a gain-control loop is formed in the receiver to maintain constant lock range and hence frequency-to-amplitude conversion ratio for the varying power of the BFSK-modulated receiver input signal. The receiver achieves the sensitivity of -87, -85, and -82 dBm for the OOK, BFSK, and DBPSK signals respectively at the data rate of 50 kb/s and the BER lower than 0.1% while consuming the power of 324 μW in total.1

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This thesis presents an ultra-low-power receiver based on the injection-locked oscillator (ILO), which is compatible with multiple modulation schemes such as on-off keying (OOK), binary frequency-shift keying (BFSK), and differential binary phase-shift keying (DBPSK). The receiver has been fabricat-ed in 0.18 µm CMOS technology and operates in the ISM band of 2.4 GHz. A simple envelope detection can be used even for the demodulation of BFSK and DBPSK signals due to the conversion capability of the ILO from the frequency and phase to the amplitude. In the proposed receiver, a Q-enhanced single-ended-to-differential amplifier is employed to provide high-gain amplification as well as narrow band-pass filtering, which improves the sensitivity and selectivity of the receiver. In addition, a gain-control loop is formed in the receiver to maintain constant lock range and hence frequency-to-amplitude con-version ratio for the varying power of the BFSK-modulated receiver input signal. The receiver achieves the sensitivity of –87, –85, and –82 dBm for the OOK, BFSK, and DBPSK signals respectively at the data rate of 50 kbps and the BER lower than 0.1 % while consuming the power of 324 µW in total This thesis presents an ultra-low power, low cost demodulator for gaussian frequency shift keying (GFSK) receivers that use low intermediate frequencies (IF). The demodulator employs a direct IF to dig-ital data conversion scheme by using an injection-locked ring oscillator (ILRO) with a 1-bit flip-flop. It consumes 2.7 μW from a 1.0 V supply at a data rate of 500 kbps achieving an energy efficiency of 5.4 pJ/bit which is 30 times better than that of the recently presented works. The demodulator also achieves 17.5 dB SNR at 0.1 % BER while operating at the same date rate. The demodulator is implemented in a 0.18 μm standard CMOS process and occupies an active area of 0.012 mm2.YⅠ. Introduction 1 1.1 Motivation 1 1.2 Design Considerations of Receiver 4 1.3 Conventional Architecture 6 1.4 Proposed Structure 12 1.5 Overview of the thesis 15 Ⅱ. Injection Locked Oscillator 16 2.1 Operation Principle 17 2.1.1 Injection Locked LC Oscillator 17 2.1.2 Injection Locked Ring Oscillator 22 2.2 Conversion Process of Injection Locked Oscillator 27 2.2.1 Amplitude to Amplitude Conversion 27 2.2.2 Frequency to Amplitude Conversion 28 2.2.3 Phase to Amplitude Conversion 29 2.2.4 Frequency to Phase Conversion 31 2.3 Summary 39 Ⅲ. A Multi-Mode ULP Receiver Based on an Injection Locked LC Oscillator 40 3.1 Overall Receiver Architecture 40 3.2 Details of the Blocks 43 3.2.1 Pre-amplifier 43 3.2.2 Single to differential amplifier 48 3.2.3 Injection Locked LC oscillator 56 3.2.4 Fully Differential Envelope Detector 59 3.2.5 Base-band Amplifier 62 3.2.6 Fully Differential Comparator 64 3.2.7 Peak Detector 68 3.3 Experimental Results 72 3.4 Summary 82 Ⅳ. Ultra-low Power GFSK Demodulator Based on an Injec-tion Locked Ring Oscillator 83 4.1 Overall Demodulator Architecture 85 4.2 Details of the Blocks 87 4.1.1 Pulse Slicer 87 4.1.2 Injection Locked Ring Oscillator 88 4.3 Experimental Results 91 4.4 Summary 96 Ⅴ. Conclusions 97 References 100 Summary (in Korean) 104DoctordCollectio

Nighttime Single Image Dehazing Based on the Structural Patch Decomposition

Images acquired from the outdoors are often degraded owing to bad weather conditions, such as haze, fog, and rain. Various algorithms for dehazing daytime images have been introduced to eliminate the effects of haze. However, unlike daytime conditions, where sunlight is the main source of light, there are multiple regional light sources in nighttime conditions. Thus, it is difficult to effectively eliminate the effects of haze at night using dehazing algorithms that primarily target daytime hazy images. In addition, most nighttime dehazing algorithms adopt the dark channel prior (DCP) to estimate the transmission, but this approach has problems due to the spatially variant illuminations. In this paper, we propose a nighttime single image dehazing algorithm based on the structural patch decomposition. First, atmospheric light is estimated by separating the intensity and color of light. To estimate the transmission, the candidates for the transmission values are set, and the final transmission value is obtained based on a weighted summation of these candidates for each image pixel. The weights of the candidates are determined according to the structural patch information of the scene radiances estimated with these candidates. Using this approach, an appropriate transmission map can be obtained, and the dehazing procedure is shown to be robust to the mixed illumination conditions observed in the nighttime conditions. The experimental results show that the proposed algorithm effectively eliminate the effect of haze in images based on quantitative and qualitative evaluations

A 1-v 4.6-mw/channel fully differential neural recording front-end ic with current-controlled pseudoresistor in 0.18-mm cmos

This paper presents a fully differential implantable neural recording front-end IC for monitoring neural activities. Each analog front-end (AFE) consists of a low-noise amplifier (LNA), a variable gain amplifier (VGA), and a buffer. The output signal of the AFE is digitized through a successive approximation register analog-to-digital converter (SAR ADC). The LNA adopts the current-reuse technique to improve the current efficiency, achieving the power consumption as low as 0.95 mW. The implemented LNA has the gain of 40 dB, the low-pass cutoff frequency of 10 kHz, and the high-pass cutoff frequency of sub-1 Hz which is realized using the current-controlled pseudoresistor. The VGA controls the gain from 21.9 dB to 33.9 dB for efficient digitization while consuming the power of 0.35 mW. The buffer drives the capacitive DAC of the ADC and consumes the power of 3.28 mW. The fabricated AFE occupies the area of 0.11 mm 2 /Channel and consumes 4.6 mW/Channel under 1-V supply voltage. Each channel achieves the input-referred noise of 2.88 mV rms , the NEF of 2.38, and the NEF 2 V DD of 5.67. The front-end IC is implemented in a standard 1P6M 0.18-mm CMOS process. © 2019, Institute of Electronics Engineers of Korea. All rights reserved.1

A 1.0 V, 5.4 pJ/bit GFSK Demodulator Based on an Injection Locked Ring Oscillator for Low-IF Receivers

This paper presents an ultra-low power, low cost demodulator for gaussian frequency shift keying (GFSK) receivers that use low intermediate frequencies (IF). The demodulator employs a direct IF to digital data conversion scheme by using an injection-locked ring oscillator (ILRO) with a 1-bit flip-flop. It consumes 2.7 µW from a 1.0 V supply at a data rate of 500 kbps achieving an energy efficiency of 5.4 pJ/bit which is 30 times better than that of the recently presented works. The demodulator also achieves 17.5 dB SNR at 0.1 % BER while operating at the same date rate. The demodulator is implemented in a 0.18 µm standard CMOS process and occupies an active area of 0.012 mm2 © 1991 BMJ Publishing Group. All rights reserved.1

A neural recording amplifier based on adaptive SNR optimization technique for long-term implantation

Long-term neural recording which can consistently provide good signal-to-noise ratio (SNR) performance over time is important for stable operation of neuroprosthetic systems. This paper presents an analysis for the SNR optimization in a changing environment which causes variations in the tissue-electrode impedance, Zte. Based on the analysis result, a neural recording amplifier (NRA) is developed employing the SNR optimization technique. The NRA can adaptively change its configuration for in situ SNR optimization. The SNR is improved by 4.69% to 23.33% as Zte changes from 1.59 MQ to 31.8 MQ at 1 kHz. The NRA is fabricated in a 0.18-μm standard CMOS process and operates at 1.8-V supply while consuming 1.6 μA It achieves an input-referred noise of 4.67 μVrms when integrated from 1 Hz to 10 kHz, which leads to the NEF of 2.27 and the NEF2VDD of 9.28. The frequency reponse is measured with a high-pass cutoff frequency of 1 Hz and a low-pass cutoff frequency of 10 kHz. The midband gain is set to 40 dB while occupying 0.11 mm2 of a chip area. © 2017 IEEE

Phase-controlled growth of cobalt oxide thin films by atomic layer deposition

Cobalt oxide (CoOx) thin films were deposited on thermally grown SiO2 substrates by atomic layer deposition (ALD) using bis(1,4-di-iso-propyl-1,4-diazabutadiene)cobalt (C16H32N4Co) and oxygen (O-2) as reactants at deposition temperatures ranging from 125 to 300 degrees C. X-ray diffraction (XRD) and Raman spectroscopic analysis indicated that a mixed-phase oxide consisting of CoO and Co3O4 was deposited at temperatures ranging from 125 to 250 degrees C. However, single-phase Co3O4 was deposited above the deposition temperature of 275 degrees C. Further, analyses by Rutherford backscattering spectrometry, transmission electron microscopy, and selected area electron diffraction along with XRD and Raman spectroscopy revealed that the single-phase cobalt oxide film was stoichiometric crystalline (spinel structure) with negligible N and C impurities. The optical band gap of the single-phase Co3O4 film was 1.98 eV and increased with decreasing deposition temperature. It was also shown that the mixed-phase cobalt oxide thin films could be converted into single-phase spinel Co3O4 by annealing at 350 degrees C in O-2 ambient. It was further observed that the phase of the ALD-grown cobalt oxide thin film could be controlled by controlling the precursor or reactant pulsing condition. The study revealed that pure Co3O4 phase could be grown at a relatively low temperature (250 degrees C) by using water vapor as a reactant. Therefore, this work systemically demonstrated several pathways to grow single-phase Co3O4 by ALD using a novel metalorganic cobalt precursor