A simple sinusoidal quadrature oscillator using a single active element

This study describes a simple design for a single active element sinusoidal oscillator with a quadrature signal. A current conveyor transconductance amplifier (CCTA), a single resistor, and two grounded capacitors are used in the first circuit. The second circuit is improved by using a current-controlled current conveyor transconductance amplifier (CCCCTA) and two grounded capacitors without a passive resistor, which means the grounded capacitor is suitably implemented for the IC fabrication. The oscillation condition and frequency of both circuits can be controlled using the same method that concurrently adjusts the DC bias current and the resistance as well as the oscillation frequency can be independently adjusted by capacitances. The CCTA is achieved by cascading the integrated circuits (IC) AD844 and LM13700, made by Analog Devices Corporation and Texas Instruments, respectively, which are available for commercial purchase. The sinusoidal quadrature signals in the time-domain and frequency-domain can be shown with computer simulations and the results of experiments. The Monte Carlo Analysis is also utilized to examine the oscillation frequency with the influence of passive element tolerance errors. The predicted oscillation frequency has a standard variation of about 20.04 kHz, with a maximum frequency of approximately 346.89 kHz and a minimum frequency of approximately 259.09 kHz. In addition, the mean and median frequencies are 296.10 and 293.98 kHz, respectively. The results of this study indicate that computer simulation and experiment are similar to a theoretical analysis, making them suiTable for use in the teaching of electrical and electronic engineerin

Mixed-Mode Third-Order Quadrature Oscillator Based on Single MCCFTA

This paper presents a new mixed-mode third-order quadrature oscillator based on new modified current-controlled current follower transconductance amplifier (MCCFTA). The proposed circuit employs one MCCFTA as active element and three grounded capacitors as passive component which is highly suitable for integrated circuit implementation. The condition and frequency of oscillations can be controlled orthogonally and electronically by adjusting the bias currents of the active device. The circuit provides four quadrature current outputs and two quadrature voltage outputs into one single topology, which can be classified as mixed-mode oscillator. In addition, four quadrature current output terminals possess high-impedance level which can be directly connected to next stage without additional buffer circuits. The performance of the proposed structure has been verified through PSPICE simulators using 0.25 µm CMOS process from TSMC and experimental results are also investigated

Circuits for Analog Signal Processing Employing Unconventional Active Elements

Disertační práce se zabývá zaváděním nových struktur moderních aktivních prvků pracujících v napěťovém, proudovém a smíšeném režimu. Funkčnost a chování těchto prvků byly ověřeny prostřednictvím SPICE simulací. V této práci je zahrnuta řada simulací, které dokazují přesnost a dobré vlastnosti těchto prvků, přičemž velký důraz byl kladen na to, aby tyto prvky byly schopny pracovat při nízkém napájecím napětí, jelikož poptávka po přenosných elektronických zařízeních a implantabilních zdravotnických přístrojích stále roste. Tyto přístroje jsou napájeny bateriemi a k tomu, aby byla prodloužena jejich životnost, trend navrhování analogových obvodů směřuje k stále většímu snižování spotřeby a napájecího napětí. Hlavním přínosem této práce je návrh nových CMOS struktur: CCII (Current Conveyor Second Generation) na základě BD (Bulk Driven), FG (Floating Gate) a QFG (Quasi Floating Gate); DVCC (Differential Voltage Current Conveyor) na základě FG, transkonduktor na základě nové techniky BD_QFG (Bulk Driven_Quasi Floating Gate), CCCDBA (Current Controlled Current Differencing Buffered Amplifier) na základě GD (Gate Driven), VDBA (Voltage Differencing Buffered Amplifier) na základě GD a DBeTA (Differential_Input Buffered and External Transconductance Amplifier) na základě BD. Dále je uvedeno několik zajímavých aplikací užívajících výše jmenované prvky. Získané výsledky simulací odpovídají teoretickým předpokladům.The dissertation thesis deals with implementing new structures of modern active elements working in voltage_, current_, and mixed mode. The functionality and behavior of these elements have been verified by SPICE simulation. Sufficient numbers of simulated plots are included in this thesis to illustrate the precise and strong behavior of those elements. However, a big attention to implement active elements by utilizing LV LP (Low Voltage Low Power) techniques is given in this thesis. This attention came from the fact that growing demand of portable electronic equipments and implantable medical devices are pushing the development towards LV LP integrated circuits because of their influence on batteries lifetime. More specifically, the main contribution of this thesis is to implement new CMOS structures of: CCII (Current Conveyor Second Generation) based on BD (Bulk Driven), FG (Floating Gate) and QFG (Quasi Floating Gate); DVCC (Differential Voltage Current Conveyor) based on FG; Transconductor based on new technique of BD_QFG (Bulk Driven_Quasi Floating Gate); CCCDBA (Current Controlled Current Differencing Buffered Amplifier) based on conventional GD (Gate Driven); VDBA (Voltage Differencing Buffered Amplifier) based on GD. Moreover, defining new active element i.e. DBeTA (Differential_Input Buffered and External Transconductance Amplifier) based on BD is also one of the main contributions of this thesis. To confirm the workability and attractive properties of the proposed circuits many applications were exhibited. The given results agree well with the theoretical anticipation.