http://hdl.handle.net/123456789/10357 Sat, 14 Mar 2026 16:24:34 GMT 2026-03-14T16:24:34Z http://hdl.handle.net/123456789/19956 Design of An Ultra-Low-Power Bluetooth Low-Energy Receiver Front end Building Blocks Muhammad Faisal Siddiqui, 02-281172-002 This research presents the design and optimization of a 2.4 GHz inductor-less, ultralow-power radio frequency (RF) front-end tailored for Internet of Things (IoT) applications, featuring a Gilbert double-balanced mixer, a low-noise amplifier (LNA), and a cross-coupled LC voltage-controlled oscillator (VCO). The growing adoption of IoT technologies, including Bluetooth Low Energy (BLE) and ZigBee, has heightened the demand for efficient, compact, and low-power RF circuits to extend battery life and reduce system costs. Implemented in a 65-nm CMOS process, these designs prioritize power efficiency, compactness, and performance. The proposed VCO employs a cross-coupled LC topology integrated with a D flip-flop frequency divider to achieve ultra-low-power consumption and excellent phase noise performance. Consuming only 0.47 mW, the VCO delivers a low phase noise of −118.36 dBc/Hz at a 1 MHz offset frequency. The VCO and frequency divider system operates with a total power consumption of just 2.02 mW and occupies an active chip area of 0.47 mm², demonstrating its suitability for system-on-chip (SoC) integration. The inductor-less Gilbert double-balanced mixer employs advanced current reuse techniques to enhance efficiency, achieving a high conversion gain of 17.38 dB, a noise figure of 7.34 dB, and substantial RF-to-IF and RF-to-LO isolation values of - 43.147 dB and -86.019 dB, respectively. It exhibits excellent linearity with an input thirdorder intercept point (IIP3) of -10.0 dBm and a 1 dB compression point of -2.57 dBm. The mixer consumes only 2.3 mW of power and occupies an ultra-compact chip area of 0.01007055 mm², making it ideal for space-constrained applications. Complementing the mixer and VCO, the LNA improves overall receiver performance by ensuring high signal sensitivity and low noise. Operating at 2.4 GHz, the LNA achieves a high gain of 28.059 dB, an input reflection coefficient of -13.5 dB for optimal impedance matching, and a low noise figure of 4.2 dB to minimize signal degradation. The LNA’s input third-order intercept point (IIP3) of -10.45 dBm ensures robust linearity, allowing it to handle large signals without distortion, further enhancing signal integrity. The chip's active area, including the pads, is only 0.00504 mm2. Together, these components address the critical design considerations for RF receivers, such as power efficiency, compactness, noise performance, and linearity. The designs’ minimal power consumption, compact chip areas, and superior performance metrics make them well-suited for BLE and ZigBee transceivers, particularly in applications demanding low cost and long battery life. By eliminating inductors, the designs reduce manufacturing complexity and chip size while enhancing scalability for future technologies. The combination of low power, high performance, and integration flexibility positions these components as strong candidates for modern IoT applications. This research contributes to the advancement of ultra-low-power RFIC solutions, meeting the growing demand for efficient and cost-effective receivers in the rapidly expanding IoT ecosystem. The thesis presents an ultra-low-power receiver frontend design using Cadence Virtuoso and CMOS 65-nm technology, including schematics, pre-layouts, and post-layouts. Supervised By Prof. Dr. Haroon Rasheed Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/123456789/19956 2025-01-01T00:00:00Z http://hdl.handle.net/123456789/19957 Design of Modular Multilevel Converter for Enhancement of Electrical Energy Efficiency in Smart Grid System Fazal Muhammad, 02-281191-001 Power distribution networks frequently experience power quality issues due to transient voltage sag originating from the upstream grid. Voltage sag is one of the major concerns of modern industry, as it can interrupt sensitive electrical loads and in the worst case cause production problems. Various technologies are used to mitigate power quality issues due to transient voltage sag such as DVR, SVC, and UQPC but they increased the complexity and cost of the system. MMC is a state-of-the-art power electronics-based technology with outstanding features of power quality and low cost. The aim of this thesis is to explore the feasibility of the power quality conditioning system based on a back-to-back Modular Multilevel Converter (MMC) to overcome voltage sag and ensure satisfactory power delivery to the distribution network. In this thesis, an MMC is designed to mitigate voltage sag due to symmetrical and asymmetrical faults in the upstream AC grid using the integrated energy of its sub-modules. In addition, the designed MMC is highly scalable and reliable, having low harmonic distortion and reactive power support. The significant outcomes of the proposed MMC-based voltage sag mitigation are cross-referenced with the other methods adapted for voltage sag mitigation in the literature. The designed converter is also one of the best options for future DC grids due to its many advantages. The designed converter is fault-tolerant and meets the challenges of Fault Ride-through (FRT) capability to avoid short-term outages caused by faults in AC or DC networks. In this research, a Fault Ride-through (FRT) strategy is proposed by converting 10% redundant submodules to full-bridge submodules during a fault scenario. The proposed strategy is framed in conjunction with the DC circuit breaker to accomplish economically viable operations and respond quickly to the system during the pole-to-pole and pole-to-ground DC faults. It is concluded that the proposed FRT strategy is economically viable. Moreover, the power loss of semiconductor devices within the submodules of the designed MMC, losses of the IGBT module, and the free-wheeling diode are analyzed when the switching frequency, power factor (p.f) and modulation index of the system are changed. The power losses of MMC have been examined for the four-quadrant operations i.e. inverter (inductive), rectifier (inductive), rectifier (capacitive), and inverter (capacitive). The evaluation of the power losses has been carried out employing PLECS to examine the losses of the designed MMC. In addition, the power loss of the designed MMC is compared with the power loss of the other conventional MMCs. It is concluded that the power losses of the designed MMC are less than those of the other conventional MMCs. Finally, it is concluded that the contributions of this research can be used in many practical and industrial applications. In terms of industrial specifications, this research meets the power quality requirements of industrial load for its efficient and economical operation meeting power quality standards. It provides a FRT strategy that economically overcomes the short-term outages caused by faults in AC and DC distribution networks. It can also be used for HVDC Back-to-back systems operating in islanded mode. Supervised by Prof. Dr. Haroon Rasheed Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/123456789/19957 2025-01-01T00:00:00Z http://hdl.handle.net/123456789/20048 Spectrum Allocation Techniques for 6th Generation Dense and High Data Rate Wi-Fi Networks Abdul Rehman, 01-281172-004 Wireless Local Area Networks (WLANs), commonly referred to as Wi-Fi, serve the increasing demands of data-centric Internet applications. The IEEE 802.11ax standard, also known as Wi-Fi 6, introduces the High-Effciency WLAN (HEW) concept to enhance network capacity, spectral effciency, and user experience, particularly in dense user environments, by implementing Orthogonal Frequency Division Multiple Access (OFDMA)-based Random Access (UORA). Despite the spectral utilization improvements offered by OFDMA, dense scenarios such as urban streets, shopping malls, sports stadiums, and conference centers still pose effciency challenges to Wi-Fi 6 due to increased contention at the Medium Access Control (MAC) layer. This thesis addresses the channel access issues for both single-channel and multiple-channel random access stations in up-link transmission mode within dense Wi-Fi 6 networks. A detailed examination of spectrum or channel allocation techniques is presented to explore various solutions ranging from distributed to centralized approaches for uplink single-channel and multi-channel random access in dense Wi-Fi networks. A distributive channel Collision-based Window Scaled Back-off (CWSB) mechanism is proposed to improve channel resource allocations for single-channel random access stations in dense WLANs. It optimizes contention window sizes for each back-off stage based on the recent data frame’s transmission status and is analytically evaluated using an Iterative Discrete-Time Markov Chain (I-DTMC) model. This approach signifcantly improves network performance in terms of improved throughput and delay reduction. In addition to the distributed solution for single-channel random access, a centralized heuristic OFDMA back-off (HOBO) UORA mechanism is proposed for multiple-channel random access stations in Wi-Fi 6. The HOBO scheme adjusts the OFDMA back-off procedure globally using only resource units, controlled by the access point, to minimize collision probabilities based on network density or user congestion level. Simulations demonstrate enhanced channel effciency and performance metrics in Wi-Fi 6 networks. Lastly, a Collision-based Distributed OFDMA Back-Off Control (CODOBO_CTRL) scheme is proposed for multiple-channel random access stations in UORA mode in Wi-Fi 6. This scheme dynamically adjusts the OFDMA back-off counter based on the recent transmission success or failure and network parameters, aiming to mitigate collisions in highly dynamic environments. Simulation-based evaluation confrms its effectiveness in managing OFDMA back-off operations in highly dynamic and congested Wi-Fi 6 environments. v Supervised by Prof. Dr. Faisal Bashir Hussain Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/123456789/20048 2025-01-01T00:00:00Z http://hdl.handle.net/123456789/18639 Control of Hybrid AC-DC Microgrid Using Variable Weighing Factor Algorithm Syed Umaid Ali, 01-281172-006 The electricity system is facing a structural transformation due to initiatives such as an increasing penetration of renewable distributed generation (RDG) units, widespread use of different converter topologies for storage, generation & loads, increased utilization of DC generation & load, led to inception of hybrid AC-DC network. This posted significant challenge in terms of its control and optimization. Moreover, Bidirectional Interlinking Converters (BICs) are used for flexible power interaction between AC and DC networks in hybrid AC-DC; both of them thus form a hybrid AC-DC network. Control of the network, especially the control of BIC, must ensure the vital coordination between AC and DC networks to achieve the key objective of appropriate power allocation amongst all the converters. Researchers have shown considerable interest in this promising area due to the non-triviality of the control design. Researchers are using multiple BICs with coordinated control or single BIC with multiple layer Proportional Integral Derivative (PID) control schemes for BIC to act as grid supporting grid forming (GSGFM) or grid-supporting grid feeding (GSGFE) unit. Moreover, fixed roles has been assigned to RDG and BESS based bidirectional DC-DC converter (BDDC). In this thesis, there are two major contributions related to the control of hybrid network: first being is to present Model Predictive Control (MPC) based control for hybrid network. A simple model for the BIC has been used through which it can act as grid supporting GSGFM unit to regulate either AC-DC voltage or GSGFE unit to regulate ACDC power sharing. The efficacy of proposed controller is simulated with realistic considerations and show improved steady state and transient performance with more accurate power allocation amongst all the converters along with detailed comparison with traditional PI based dual-droop control. The second part of our work considers converter-based DC microgrids comprising of RDG and battery energy storage systems (BESS), which are being integrated into power systems infrastructure at rapid pace. For better performance and reliable operations, it is envisioned that RDG, BESS along with loads will form microgrids which can strengthen grid resilience, operate autonomously while the main grid is down, help mitigate grid disturbances as well as function as a grid resource for faster system response and recovery. For autonomous operation power converters will be assigned the role of Grid Supporting Grid Forming (GSGFM) units for voltage regulation and Grid Supporting Grid Feeding (GSGFE) units for current regulation. The architecture of a consensus-based energy management system (EMS) is presented with MPC based variable weighing factor algorithm for power converters of RDG and BESS to act as GSGFM DG or GSGFE DG for both islanded and grid-connected mode. Taking existing control schemes, their voltage regulation capability (GSGFM), current regulation capability (GSGFE) and mode changing capability is discussed to maximize the usage and improve the performance of power converters. The basic design principal of our proposed EMS is to maximize the usage of controllers of all the DG units of microgrid by assigning them the role of GSGFM DG or GSGFE DG as per their power handling capacity and grid loading conditions; thus, achieving the good steady-state performance with THD less than 1.1% and quick dynamic response with settling time less than 0.06 sec. These results will help in achieving the reliable and autonomous operation of hybrid MG with multiple DGs. Pakistan is the sixth largest nation in the world with around 51 million people (20% of the population) living off grid with no access to electricity. The proposed algorithm will aid in offering the offgrid solution to those areas, which are not connected to the grid. Supervised by Dr. Asad Waqar Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/123456789/18639 2024-01-01T00:00:00Z