DESIGN AND IMPLEMENTATION OF IMMITTANCE CIRCUITS USING ACTIVE BUILDING BLOCKS

Abstract

The discipline of analog signal processing has experienced significant growth and development during the past few decades. The literature describes a variety of voltage-mode and current-mode active components for carrying out analog signal processing tasks. Nevertheless, the analog signal processing circuits in the current domain offers advantages such as enhanced bandwidth, less circuit complexity, expanded dynamic, low power consumption, and high speed. Therefore, the current-mode approach is widely recognized as a viable alternative to conventional voltage-mode circuits. The immittance circuits have numerous applications in microelectronics, communication, analog signal processing, instrumentation, and measurement. There are limitations of realizing traditional components namely inductor and resistor in microelectronics circuits, such as occupying significant chip space, being heavy, expensive, and lacking tunability. It makes the active immittance circuits, a prominent area of study. This thesis deals with design of immittance emulators and their applications. A variety of integer order immittance emulators have been developed in the literature. However, there is a lean presence of emulators that simultaneously fulfil the following criterions: tunability, no matching constraint, less components, low power consumption, low chip area, and working in positive and negative mode without topological changes. In addition, it is pertinent to mention here that to obtain positive and negative modes the topological change is not possible once the circuit is laid down and fabricated. Also, if two different circuits are realized in IC form for positive and negative immittances, the resulting silicon footprint would require more. Hence, Current Conveyor Transconductance Amplifier (CCTA) based a grounded and floating immittance emulators are developed that provides both positive and negative immittances through appropriate setting of MOS switches. The proposed topology does not require any component matching, thus making it suitable for integration viewpoint. Further, these immittance emulators are tuned electronically via bias current of CCTA. The proposed immittance circuit is used to implement the fifth order low pass filter, and capacitance cancellation circuit. iv Nowadays, fractional order circuits gain considerable attention among researchers due to the extra degree of freedom to control the phenomena of the system. The fractional order inductor circuits reported in literature are limited in terms of large number of active and passive components, tunability, slew rate, operating frequency, and high-power dissipation. Hence, Operational Transconductance Amplifier (OTA) based electronically tunable grounded and floating fractional order inductor circuits are also developed. These circuits can flip between positive and negative modes without modifying their architecture. The usefulness of the proposed positive fractional inductor circuit is demonstrated through fractional order band pass filter and fractional order high pass ladder filter. The usefulness of the proposed negative fractional inductance circuit is demonstrated through a fractional inductance cancellation circuit. The synthetic transformer (ST) circuit or Mutual Coupled Circuit (MCC) is yet another application of immittance circuit. It is frequently used in circuits for instrumentation, measurement, analog communications, and signal processing. It is observed that MCC circuit featuring mutual inductance in four different pairs like passive transformer is not available in open literature. To fill this gap, a CCTA based tunable floating MCC is designed which can be configured in four different pairs of mutual coupled circuits through appropriate setting of MOS switches. The proposed MCC does not require component matching condition. Self-inductance, mutual inductance, and resonant frequency can be tuned by bias current of CCTA. A double tuned band pass filter is shown as an application. Furthermore, memristor is the fourth fundamental element in circuit theory after resistor, capacitor, and inductor. It is gaining considerable attention among researchers due to its high-density storage property. It is a non-linear device provides relation between electric charge (q) and magnetic flux (φ). A solid state memristor is not available in the market due to its high price and difficult manufacturing process. Hence, charge and flux controlled memristor emulators are developed employing Inverting Current Conveyor Transconductance Amplifier (ICCTA). In addition, both proposed circuits do not include intricate components such as analog multiplier circuits, passive inductors, and analog to digital converter circuits in their design, which is beneficial in terms of integrated circuit implementation point of view. Further, the effectiveness of the developed circuits is validated using meminductor circuits, and memristor-based active filters. v The behavior of the proposed circuits is analyzed in the presence of parasites that may appear in practice. The operation has been examined through SPICE simulations and post-layout simulations are also included in the thesis. Corner and Monte-Carlo analysis is performed to assess the robustness of the various proposals.