REALIZATION OF VARIOUS LINEAR AND NON LINEAR APPLICATIONS USING CURRENT MODE BUILDING BLOCKS

Abstract

The rapid evolution of semiconductor technology has enabled the integration of millions of transistors on a single chip, diminishing the gaps between analog and digital domains. This trend has led to the rise of integrated solutions that incorporate both analog and digital subsystems on a single die. Despite a significant shift towards digital circuit design over the past two decades, analog design remains essential, particularly for functions such as signal processing, amplification, filtering, and conversion between analog and digital signals. The demand for high-performance analog interface circuits continues to grow with the emergence of new applications. Designing analog circuits faces challenges due to the ongoing scaling of device dimensions and power supply voltages. Reduced power supply voltages can limit input common-mode range, linearity, and output voltage swing. Analog circuits can be classified as voltage mode (VM) or current mode (CM) based on whether they process information via nodal voltages or branch currents. Scaling adversely affects VM circuits' performance parameters, including dynamic range, slew rate, and common mode range. In contrast, CM circuits offer enhanced slew rate, wider bandwidth, and better dynamic range due to smaller time constants and the ability to utilize transistors up to their unity-gain bandwidth. Additionally, CM circuits can be more compact, as current addition is achieved by simply connecting branches. To leverage the advantages of CM signal processing, various analog building blocks have been developed. Components like Differential Difference Current Conveyors (DDCC), Differential Difference Current Conveyor Transconductance Amplifiers (DDCCTA), and Extra-X Current Controlled Current Conveyor Transconductance Amplifiers (EXCCCCTA) combine the features of current conveyors and current feedback operational amplifiers, with added current outputs to enhance design flexibility. These blocks are well-suited for processing and delivering both current and voltage at appropriate impedance levels, making them invaluable in modern analog circuit design. vi A novel voltage-mode First Order Universal Filter (FOUF) utilizing a single DDCC combined with one resistor and one capacitor is presented. The proposed FOUF, designed as a multiple-input single-output (MISO) configuration, provides low-pass, high-pass, and all-pass responses, achieving a pole frequency of Mega Hz. Additionally, the application of the filter in a trans-admittance mode (TAM) controller is presented. This TAM controller employs Proportional-Derivative (PD), Proportional-Integral (PI), and Proportional-Integral-Derivative (PID) configurations, utilizing a DDCCTA with three resistors and three capacitors. Key features include the use of grounded capacitors and independent electronic tuning of control parameters, enabling simultaneous PD, PI, and PID operations. The study explores the impact of DDCCTA non-idealities on the controller and demonstrates an enhanced gain frequency response. The controller's effect on the step response of a DDCCTA-based second-order filter system is analyzed to validate its practical application. Two novel designs for wave active filters (WAF) based on voltage mode and current mode configurations are presented. The first design utilizes a DDCC to implement a wave-active filter, with wave quantity processing forming the foundation of its operation. The DDCC serves as the analog building block (ABB) for executing mathematical operations such as lossy integration-subtraction, subtraction, summation, and inversion, which are essential for creating wave-active components like series inductors and shunt capacitors. This design is applied to develop low to high-order low-pass Butterworth filter topologies, with theoretical verification is provided for nth-order low-pass Butterworth filters (n = 2, 3, 4, 5, 6). The second design introduces a current-mode wave active filter employing the EX-CCCCTA. This approach features a simplified design using a single EX-CCCCTA, grounded passive components, and electronic tuning capabilities, making it well-suited for high frequency applications up to approximately Mega Hz. Compared to passive filters, this current-mode WAF offers advantages such as tunable gain, compatibility with monolithic integration, and optimal input-output impedance. Both filters' performance is validated through Monte Carlo analysis, THD assessment, and noise analysis, demonstrating its efficacy in practical applications. vii The CM full-wave rectifiers (FWR) use two distinct analog building blocks: DDCC and DDCCTA. The first design employs a DDCC, two MOS-based diodes, and three grounded resistors to implement CM full-wave positive and negative rectifiers in different topologies, achieving an operating frequency of Mega Hertz. The second design introduces an electronically tunable, dual-output CM FWR using a single DDCCTA, two MOS-based active diodes, and four grounded active resistors. A key advantage of this design is its high output impedance with dual outputs (positive and negative) simultaneously, enabling easy cascading with other circuits. The work thoroughly analyzes the effects of non-idealities, including non-unity transfer gains and parasitic elements, on the circuit's performance. Additionally, Monte Carlo simulations are performed to validate the robustness and practical applicability of the proposed designs. To evaluate functionality and performance, SPICE and Virtuoso simulators are used with 180 nm TSMC CMOS technology and 180 gpdk parameters, respectively. Various simulations are carried out to demonstrate the effectiveness of all proposed designs.