Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/143502
Title: High-voltage IR-UWB pulse generator MMIC design and beamforming for indoor-ranging and radar applications
Authors: Hussain Ansari Md Arif
Keywords: Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
Issue Date: 2019
Publisher: Nanyang Technological University
Source: Hussain Ansari Md Arif. (2019). High-voltage IR-UWB pulse generator MMIC design and beamforming for indoor-ranging and radar applications. Doctoral thesis, Nanyang Technological University, Singapore.
Abstract: In recent times, impulse-radio ultra-wideband (IR-UWB) systems have gained significant attention for indoor positioning and short-range radar applications due to many of their inherent properties like ultra-fine temporal resolution, non-line-of-sight detection, multipath immunity, low power consumption, low-cost, etc. The critical challenge for the IR-UWB based systems is to generate an IR-UWB pulse, which is shorter in time and higher in amplitude. In particular, for the indoor-ranging and radar applications, the limited peak power of an IR-UWB pulse restricts the line-of-sight (LOS) range, non-line-of-sight (NLOS) detection and degrades radar imaging. In this thesis, two levels of improvement are proposed and demonstrated. Firstly, an MMIC design is presented at the chip-level to achieve higher peak power directly from the chip. Secondly, novel beamforming techniques are proposed, which superimpose transmitted pulses spatially to produce strong radiating beams. Finally, the proposed beamforming networks are optimized and prototyped. The generation of the IR-UWB pulse is carried out through two successive stages on the MMIC, called as the impulse generator and the pulse former. The impulse generator generates a 7V sub-nanosecond voltage pulse, which is being used as an input to the pulse former stage. The pulse former performs the signal scaling, time-shifting, amplitude-reversal, and signal-addition to produce the desired Gaussian-enveloped multi-cycle IR-UWB pulse. The systematic circuit analysis is performed, and the effect of coupling capacitors on the amplification factor as well as impedance profile at each stage of pulse former are discussed in detail. In addition to this, the effect of temperature-dependent parasitic on the transient behaviour of the proposed IR-UWB pulse generator is analyzed, and the required mathematical model is derived. The proposed circuit is optimized for the highest possible output peak-power in the 3-5 GHz UWB band. The presented design is fully utilizing the existing 2 µm GaAs HBT cascode pair configuration, which significantly increases the output voltage swing while reducing the total power consumption. The measured output pulse has a peak-to-peak voltage of 10.2 V for a 50 Ω load. The proposed pulse generator MMIC has a total power consumption of 122 µW at 100 kHz pulse repetition frequency and power efficiency of 9.8% (18.4%). In order to further improve the peak power level in desired directions, the beam-pattern analysis of an electronically steerable multi-beam IR-UWB transmitter tag suited for real-time positioning systems is presented and demonstrated. Two linear arrays of four elements with an inter-element spacing of 18 cm and 10.2 cm are proposed and optimized. The array with a spacing of 10.2 cm is intentionally configured to produce orthogonal beams, which eventually provides better geometric dilution of precision (GDOP). The beam steering-angle analysis and an intensity table for the Gaussian-modulated multi-cycle IR-UWB beamforming array are provided. The proposed beamforming transmitter arrays are observed to achieve the scanning range from –60⁰ (–90⁰) to +60⁰ (+90⁰) with a scanning resolution of 5⁰ and 8⁰ in the measurements. In addition to this, a novel algorithm for the separation between distributed wireless sensor nodes of the virtual non-linear array is proposed for collaborative beamforming in the wireless sensor network system. The proposed algorithm can produce a single beam radiation pattern of the collaborative virtual radar array. The presented radiation pattern is proposed for Gaussian-shaped multi-cycle IR-UWB beamforming, which effectively reduces the grating lobes despite electrically large separation between the transmitting nodes. A random error of positioning for sensor nodes and random jitter for different IR-UWB pulse is incorporated in the analysis, and related simulation results are provided. A prototype for the time domain beam-pattern measurement is developed for proof-of-concept. The measurement results show better than 6dB suppression for side lobes radiation.
URI: https://hdl.handle.net/10356/143502
DOI: 10.32657/10356/143502
Schools: School of Electrical and Electronic Engineering 
Rights: This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:EEE Theses

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