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In advanced applications such as satellite telecommunications, digital radar, frequency hopping data links and micro-wave communications, powerful signal processors able to handle broadband signal vectors are becoming more common. The bottleneck is now the availability of high sampling rate and high linearity data converters, ADCs (Analog to Digital Converter) for reception and DACs (Digital to Analog...
This paper describes a higher-order ΔΣ time-digital converter (TDC) design for high resolution UWB radar systems. To overcome “cross boundary” issue and in 1-bit first-order ΔΣ TDC, a 3-bit second-order ΔΣ TDC is proposed. For digitalintensive robust phase tracking, a dual delay lock loop (DLL) is adopted in which a digital phase rotator is designed to provide an unlimited phase capture range. The...
This paper proposes a Monte - Carlo based statistical simulation technique for estimating the error probability for different modulation schemes of a log-normal Raleigh fading channel in a digital wireless communication network. The generalised expressions which are found in the literature involve not only tedious mathematical analysis and lengthy computational time but also need to be re-derived...
Rayleigh backscattering (RB) noise is a fundamental limitation for a centralized loopback WDM-PONs based on RSOA in ONU side. By exploring the RSOA chirp induced spectral boarding with DC-balanced line coding, here a novel modulation format called as Coded RZ is proposed to enhance the system tolerance against RB. The results showed that the signal-to-noise (SCR) is improved by about 8 dB and 2.5...
Sigma-Delta modulators are commonly used in applications that require high resolution. In this paper a IV second order sigma delta ADC is presented. In this paper over sampling concept is used to address the problem of power dissipation and noise in ADCs. A second order sigma delta modulator is implemented using CMOS 130nm technology. Oversampling ratio is 128 and total power dissipation is found...
The paper describes an approach for semi-symbolic analysis of mixed-signal systems that contain discontinuous functions, e.g. due to modeling comparators. For modeling and semi-symbolic simulation, we use extended Affine Arithmetic. Affine Arithmetic is currently limited to accurate analysis of linear functions and mild non-linear functions, but not yet discontinuities. In this paper we extend the...
Envelope tracking (ET) RF power amplifiers are emerging from decades of research as practical approaches for highly efficient, highly linear, broadband power amplification. Many aspects of ET power amplifiers are ideally suited for modern wireless communications - they work well across a wide frequency range, they are amenable to high levels of integration at the mobile terminal level, and they will...
Pipeline Analog to Digital Converters (ADCs) are widely used in applications that require medium to high resolution at high acquisition speed. Despite of their quite simple working principles, they usually form rather complex mixed-signal blocks, particularly if digital correction and calibration are considered. As a result, pipeline converters are difficult to test and diagnose. In this paper, we...
WiMAX is a broadband wireless technology based on IEEE802.16 standards family, which defines the physical (PHY) and medium access control (MAC) layers and makes several possible configurations available along with non-mandatory options. WiMAX is a new OFDM based technology and promises to combine high data rate services with wide area coverage. In this paper, the performance of WiMAX PHY layer is...
The application of equalization schemes to Single Carrier (SC) modulation techniques has made them a valuable alternative to Orthogonal Frequency Division Multiplexing (OFDM). Equalization schemes mitigate Inter Symbol Interference (ISI) caused by multipath fading which degrades the performance of modulation schemes. In this paper we study Zero Forcing, Minimum Mean Square Error and Decision Feedback...
The design and implementation of a CMOS integrated analog to digital interface dedicated to hybrid integration of MEMS resistive microphone is presented. Audio sensing is achieved with an innovative low-cost technology that uses single crystal piezoresistive silicon nanowires as transducer in a MEMS. The circuit composed of a low-noise instrumentation preamplifier followed by a single bit fourth order...
A direct readout circuit configurable for electret or MEMS digital microphones is presented. The circuit includes a transducer interface, a programmable preamplifier, a 4th order ΣΔ modulator, a bandgap reference, a clock detection circuit, and a stability recovery system. A prototype has been realized in a 0.25μm CMOS process, performing 63dBA SINAD at 1Pa, and a consumption of 470μA at 1.6V supply...
Finding a suitable topology and Noise-transfer-function for higher order Incremental Delta-Sigma ADCs is a complex task. Estimating the performance of the ADC taking the circuit nonidealities into account by simulation requires sophisticated modeling and significant computing resources. Even with complex models, taking into account all nonidealities is not possible. This work proposes a completely...
In a multiuser channel signals are corrupted due to Additive White Gaussian Noise (AWGN) and Inter Carrier Interference (ICI). Orthogonal Frequency Division Multiplexing (OFDM) receiver detects the symbols or bits and estimates the parameters. Wavelet Packet Modulation (WPM) is applied to the received symbols that have been previously coded at the transmitter by a special code. The final result obtained...
The paper presents the design of a fully differential gain boosted operational amplifier (opamp). The opamp is designed for high performance analog-to-digital converter (ADC). Both the main opamp and the boosted opamp are fully differential folded-cascode opamp. The main opamp has a switch capacitor common mode feedback circuit. The opamp is designed in 0.13m CMOS process with 1.2V power supply. Spectre...
The recent digital transition of TV broadcasting has created new opportunities for wireless usage for voice, video and data services in these newly released bands (known as TV white spaces). Some possible wireless technologies that can be deployed in this new spectrum are LTE and Wi-Fi. In this paper, we conduct an in-depth analysis of the physical layer performance of LTE and Wi-Fi in the presence...
Vertical line arrays (VLAs) deployed below the critical depth in deep ocean environments have been shown to have lower levels of distant shipping noise [1]. In addition, acoustic energy from nearby targets travels via the Reliable Acoustic Path (RAP), and thus has an enhanced signal level. The combination of these two factors produces a favorable detection scenario. However, nearby surface ship interference...
Calcium signaling is one of the most widely studied means of providing communication for molecular communications in nanonetworks. In this paper, we investigate error control approaches for calcium signaling based molecular communications. Taking an information theoretic approach we show, using a stochastic simulation model, how error conditions such as signal fading, multipath propagation and spatial...
Quest for ultra-low power ADCs have forced researchers to push existing ADC architectures to work in ultra-low voltage supply. VCO based ADCs are promising solutions to address this problem since continuous scaling in CMOS technology aids their highly digital nature and time-based architectures. However, VCO-based ADCs have various challenges for achieving ultra-low power targets such as small voltage...
Multi-stAge noise SHaping (MASH) based Digital Delta-Sigma Modulator (DDSM) architecture is widely used in Fractional-N Frequency Synthesizers. However, the DDSM is a Finite State Machine (FSM) with a constant input, and its output sequence presents an intrinsic periodicity, this structure is apt to generate spur tones around the carrier. This paper proposes a novel method to implement an improved...
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