Illumination waveform optimization for time-of-flight range imaging cameras

Time-of-flight range imaging sensors acquire an image of a scene, where in addition to standard intensity information, the range (or distance) is also measured concurrently by each pixel. Range is measured using a correlation technique, where an amplitude modulated light source illuminates the scene and the reflected light is sampled by a gain modulated image sensor. Typically the illumination source and image sensor are amplitude modulated with square waves, leading to a range measurement linearity error caused by aliased harmonic components within the correlation waveform. A simple method to improve measurement linearity by reducing the duty cycle of the illumination waveform to suppress problematic aliased harmonic components is demonstrated. If the total optical power is kept constant, the measured correlation waveform amplitude also increases at these reduced illumination duty cycles. Measurement performance is evaluated over a range of illumination duty cycles, both for a standard range imaging camera configuration, and also using a more complicated phase encoding method that is designed to cancel aliased harmonics during the sampling process. The standard configuration benefits from improved measurement linearity for illumination duty cycles around 30%, while the measured amplitude, hence range precision, is increased for both methods as the duty cycle is reduced below 50% (while maintaining constant optical power)

Stability analysis with Pole-zero Identification: unveiling the critical dynamics of microwave circuits

The term pole-zero identification refers to obtaining the poles and zeros of a linear (or linearized) system described by its frequency response. This is usually done using optimization techniques (such as least squares, maximum likelihood estimation, or vector fitting) that fit a given frequency response of the linear system to a transfer function defined as the ratio of two polynomials [1], [2]. This kind of linear system identification in the frequency domain has numerous applications in a wide variety of engineering fields, such as mechanical systems, power systems, and electromagnetic compatibility. In the microwave domain, rational approximation is increasingly used to obtain black-box models of complex passive structures for model order reduction and efficient transient simulation. An extensive bibliography on the matter can be found in [3]-[6]. In this article, we focus on a different application of pole-zero identification. We review the different ways in which pole-zero identification can be applied to nonlinear circuit design, for power-amplifier stability analysis, and more. We provide a comprehensive view of recent approaches through illustrative application examples. Other uses for rational-approximation techniques are beyond the scope of this article.This work was supported in part by the French Space Agency (CNES) under projects R-S10/TG-0001-019 and R-S14/TG-0001-019; by a joint Ph.D. research grant from CNES and Thales Alenia Space, France; by project TEC2015-67217-R (MINECO/FEDER); and by the Basque Country Government through project IT1104-16

Linearization techniques to suppress optical nonlinearity

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis is shown the implementation of the linearization techniques such as feedforward and pre-distortion feedback linearization to suppress the optical components nonlinearities caused by the fibre and semiconductor optical amplifier (SOA). The simulation verified these two linearization techniques for single tone direct modulation, two tone indirect modulation and ultra wideband input to the optical fibre. These techniques uses the amplified spontaneously emission (ASE) noise reduction in two loops of SOA by a feed-forward and predistortion linearizer and is shown more than 6dB improvement. Also it investigates linearization for the SOA amplifier to cancel out the third order harmonics or inter-modulation distortion (IMD) or four waves mixing. In this project, more than 20 dB reductions is seen in the spectral re-growth caused by the SOA. Amplifier non-linearity becomes more severe with two strong input channels leading to inter-channel distortion which can completely mask a third adjacent channel. The simulations detailed above were performed utilizing optimum settings for the variable gain, phase and delay components in the error correction loop of the feed forward and Predistortion systems and hence represent the ideal situation of a perfect feed-forward and Predistortion system. Therefore it should be consider that complexity of circuit will increase due to amplitude, phase and delay mismatches in practical design. Also it has describe the compatibility of Software Defined Radio with Hybrid Fibre Radio with simulation model of wired optical networks to be used for future research investigation, based on the star and ring topologies for different modulation schemes, and providing the performance for these configurations

Mid-Infrared Optical Frequency Combs based on Difference Frequency Generation for Molecular Spectroscopy

Mid-infrared femtosecond optical frequency combs were produced by difference frequency generation of the spectral components of a near-infrared comb in a 3-mm-long MgO:PPLN crystal. We observe strong pump depletion and 9.3 dB parametric gain in the 1.5 \mu m signal, which yields powers above 500 mW (3 \mu W/mode) in the idler with spectra covering 2.8 \mu m to 3.5 \mu m. Potential for broadband, high-resolution molecular spectroscopy is demonstrated by absorption spectra and interferograms obtained by heterodyning two combs.Comment: 11 pages, 8 figure

5G NR-밴드 무선 주파수 송수신기의 검증을 위한 모델링 방법

학위논문(석사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2021.8. 김재하.도래한 초연결시대에서는 스마트폰뿐만 아니라 다양한 사물 인터넷 디바이스들이 5세대 이동통신 시스템을 활용하면서, 늘어난 데이터량과 트래픽을 감당하기 위해 밀리미터파 대역의 사용이 필수적일 것이다. 시스템이 보다 대용량화 그리고 광대역화 됨에 따라, 통신 규약을 만족시키기 위해, 점차 거대한 디지털 캘리브레이션 및 신호처리 로직이, 무선 통신 전단부 칩에 함께 집적되고 있다. 따라서 멀티-도메인의 신호(아날로그/디지털/무선통신 신호)가 복잡하게 혼성된 무선통신 집적회로 칩을, 짧은 개발 기간 동안 충분히 검증하기엔 어려움이 따른다. 일반적으로 혼성 신호 시스템을 검증하기 위해서는, 하위 시스템을 모두 포함해서 시간 도메인의 시뮬레이션을 수행해야 하는데, 이를 위한 스파이스와 스파이스-하드웨어 기술 언어의 co-시뮬레이션은 지나치게 느리다는 한계가 있기 때문이다. 따라서, 멀티-도메인의 신호를 빠르고 정확하게 시뮬레이션 가능하게 하는 모델링 방법과, 다양한 시나리오의 검증 완성도를 향상시켜줄 있는 검증 기술이 모두 요구된다. 혼성 시스템을 검증하기 위해서는, 아날로그와 무선 통신 블록들을 시스템 베릴로그 상에서 구현된 함수적 모델로 대체하고, 디지털 블록들과 함께 하나의 디지털 플랫폼에서 시뮬레이션하는 것이 효과적이다. 실제 설계할 때, 문제가 되는 대부분의 에러들은, 연결 오류, 부호 오류, 신호 순서 오류, 혹은 잘못된 파워 도메인과의 연결과 같이 사소한 오류들이다. 이러한 오류를 찾기 위해, 오래 걸리는 트랜지스터-레벨의 시뮬레이션을 수행하기보다는, 아날로그 스파이스 모델들을 시스템 베릴로그 모델들로 대체하고, 보다 다양한 시나리오를 빠르게 검증하는 방법이 검증 완성도를 향상시키는데 적합하다. 그럼에도, 지나치게 단순한 선형 모델이나, 중요한 회로 특성이 빠진 모델로는 원하는 수준의 검증이 불가능할 수 있다. 예를 들어, 직접 변조 구조의 무선통신 송수신기에서 발생하는 비이상 효과, 저전력 동작을 하면서 발생하는 비선형 효과, 그리고 흔히 메모리 효과는 모델에 효과를 충분히 반영해 주어야만, 주파수 도메인에서의 검증, 성능 예측 등의 검증을 의미 있게 수행할 수 있다. 문제는 비선형 시스템은 훨씬 복잡한 식으로 표현되며, 시뮬레이션 시 연산량도 크게 늘어나기 때문에, 비선형 모델을 만들고 시뮬레이션 하기가 쉽지 않다는 것이다. 따라서 모델이 비이상성들을 충분히 반영하면서도 효과적인 검증을 가능하게 하는 모델링/시뮬레이션 방법 역시 요구된다. 본 학위 논문에서는, 무선통신 송수신기 집적회로 전체의 모사 모델을 제안한다. 모델은 누설 신호와 신호 간 불일치에 의한 비-이상적인 효과를 엑스모델의 알고리즘을 활용해 반영하였고, 비선형성과 메모리 효과를 볼테라-섭동법을 활용해 반영하였다. 제안하는 모델은 다양한 주파수 대역과 동작 모드를 검증하는데, 기존 등가 베이스밴드 모델보다 30~1800배 빠르게 시뮬레이션 할 수 있었고, 비이상 효과에 대해, 통신 성능들(심볼의 오류 벡터의 크기, 인접 채널의 파워 그리고 비트 에러)을 평가 가능했다. 나아가, 아날로그 검사기를 활용한 기능 검증법과 모델 파라미터 커버리지 분석법을 적용하여, 시스템-레벨 검증의 완성도를 향상시켰다. 무선통신 집적회로 모델에 다양한 디자인/파라미터 오류를 주입하고, 시뮬레이션 동안 검사기가 찾은 에러의 개수와 커버리지 결과를 실험적으로 보였다.In mobile RF transceiver systems, the large number of digital circuits employed to compensate or calibrate the non-idealities of the RF circuits call for models that can work within the digital verification platform, such as SystemVerilog. While baseband-equivalent real-number models (RNMs) are the current state-of-the-art for modeling RF transceivers in SystemVerilog, their simulation speeds and accuracy are not adequate predicting performance degradation. Since, its signals can only model the frequency components near the carrier frequency but not the DC offsets or high-order harmonic effects arising due to nonlinearities. Therefore, the growing impacts of nonlinearities call for nonlinear modeling of their key components to predict the overall system's performance. This dissertation presents the models for a multi-standard, direct-conversion RF transceiver for evaluating its system-level performance and verifying its digital controllers. Also, this work demonstrates the Volterra series model for the nonlinear analysis of a low-noise amplifier circuit in SystemVerilog, leveraging the functional expression and event-driven simulation capability of XMODEL. The simulation results indicate that the presented models, including the digital configuration/calibration logic for the 5G sub-6GHz-band and mmWave-band transceiver, can deliver 30–1800× higher speeds than the baseband-equivalent RNMs while estimating the quadrature amplitude modulation signal constellation and error vector magnitude in the presence of non-idealities such as nonlinearities, DC offsets, and I/Q imbalances. In addition, it implements functionality checkers and parameter coverage analysis to advance the completeness of system-level verification of the RF transceivers model.Chapter 1. Introduction 1 1.1 Design and Verification Flow . 1.2 5G NR Band RF Transceiver IC . 1.3 Baseband-Equivalent and Passband Modeling . 1.4 Thesis Organization . Chapter 2. Modeling and Simulation of RF Transceiver 11 2.1 Direct Conversion RF Transceiver . 2.2 Proposed Transceiver Models . 2.3 System and Simulation Performance . Chapter 3. Nonlinear RF System Modeling 28 3.1 Volterra / Perturbation Method . 3.2 Low Noise Amplifier Example . 3.3 Nonlinearity Analysis . Chapter 4. Coverage Analysis and Functional Verification 42 4.1 Model Parameter Coverage Analysis . 4.2 Self-Checking Testbench . Chapter 5. Conclusion 54 Appendix 55 A.1 Trigonometric Equation for Non-Ideal Effects . A.2 RNM Baseband Equivalent Modeling . A.3 Parameter Coverage Analysis . A.4 List of Models . Bibliography 63 Abstract in Korean 66석

Fast high fidelity quantum non-demolition qubit readout via a non-perturbative cross-Kerr coupling

Qubit readout is an indispensable element of any quantum information processor. In this work, we experimentally demonstrate a non-perturbative cross-Kerr coupling between a transmon and a polariton mode which enables an improved quantum non-demolition (QND) readout for superconducting qubits. The new mechanism uses the same experimental techniques as the standard QND qubit readout in the dispersive approximation, but due to its non-perturbative nature, it maximizes the speed, the single-shot fidelity and the QND properties of the readout. In addition, it minimizes the effect of unwanted decay channels such as the Purcell effect. We observed a single-shot readout fidelity of 97.4% for short 50 ns pulses, and we quantified a QND-ness of 99% for long measurement pulses with repeated single-shot readouts

Tunable coupling to a mechanical oscillator circuit using a coherent feedback network

We demonstrate a fully cryogenic microwave feedback network composed of modular superconducting devices connected by transmission lines and designed to control a mechanical oscillator coupled to one of the devices. The network features an electromechanical device and a tunable controller that coherently receives, processes and feeds back continuous microwave signals that modify the dynamics and readout of the mechanical state. While previous electromechanical systems represent some compromise between efficient control and efficient readout of the mechanical state, as set by the electromagnetic decay rate, the tunable controller produces a closed-loop network that can be dynamically and continuously tuned between both extremes much faster than the mechanical response time. We demonstrate that the microwave decay rate may be modulated by at least a factor of 10 at a rate greater than $10^4$ times the mechanical response rate. The system is easy to build and suggests that some useful functions may arise most naturally at the network-level of modular, quantum electromagnetic devices.Comment: 11 pages, 6 figures, final published versio

An improved reversed miller compensation technique for three-stage CMOS OTAs with double pole-zero cancellation and almost single-pole frequency response

This paper presents an improved reversed nested Miller compensation technique exploiting a single additional feed-forward stage to obtain double pole-zero cancellation and ideally single-pole behavior, in a three-stage Miller amplifier. The approach allows designing a three-stage operational transconductance amplifier (OTA) with one dominant pole and two (ideally) mutually cancelling pole-zero doublets. We demonstrate the robustness of the proposed cancellation technique, showing that it is not significantly influenced by process and temperature variations. The proposed design equations allow setting the unity-gain frequency of the amplifier and the complex poles' resonance frequency and quality factor. We introduce the notion of bandwidth efficiency to quantify the OTA performance with respect to a telescopic cascode OTA for given load capacitance and power consumption constraints and demonstrate analytically that the proposed approach allows a bandwidth efficiency that can ideally approach 100%. A CMOS implementation of the proposed compensation technique is provided, in which a current reuse scheme is used to reduce the total current consumption. The OTA has been designed using a 130-nm CMOS process by STMicroelectronics and achieves a DC gain larger than 120 dB, with almost single-pole frequency response. Monte Carlo simulations have been performed to show the robustness of the proposed approach to process, voltage, and temperature (PVT) variations and mismatches