A Linear VCO Using Single CFA and Analog Multipliers: Quadrature Oscillator Implementation

A new linear voltage-controlled oscillator (LVCO) implementation using single AD-844 CFA with a pair of AD-835 multiplier devices and a pair of grounded capacitors is proposed. The open-loop transfer function of the topology is analyzed wherein the concept of Short-Circuit Natural Frequency (SCNF) is applied to derive the sinusoid oscillator implementation. The proposed oscillator circuit is then restructured to yield a linear voltage-controlled quadrature oscillator (LVCQO) after appropriate cascade with a CFA-based active integrator. The oscillation frequency is linearly tunable ([Formula: see text][Formula: see text]MHz) by the multiplier control voltage ([Formula: see text]. Subsequently, a high-[Formula: see text] selective band-pass (BP) filter is derived. Effects of the CFA port roll-off parameters and its parasitic capacitors ([Formula: see text] had been analyzed to be negligible. Measured oscillator response exhibited a THD [Formula: see text]%, a linearity error ([Formula: see text]% and a phase noise figure of ([Formula: see text]104 dBc/Hz at 24-kHz offset.

Designing of a Quadrature Oscillator

This paper is an attempt to design and develop an electronic circuit for Quadrature Oscillator, by using locally available components, to be used in servicing of display units for maintenance of a network of 14 Nos. of SAMEER R/Ts in IMD’s upper air network of 39 radiosonde radiowind observation system.

CMOS Realizable and Highly Cascadable Structures of First-Order All-Pass Filters

Two novel resistorless structures of a first-order voltage-mode all-pass filter are presented in the paper. Both the structures employ a fully differential second-generation current conveyor (FDCCII) as the primary active element, in addition to an active resistor. A grounded capacitor is the only passive component used in both the structures. In both the structures, CMOS realization of FDCCII is utilized; hence, these structures are CMOS compatible. Some of the other highly demanded features possessed by the presented all-pass structures are: a simple circuit topology, electronic tunability, high input impedance, constraint-free operation in terms of passive component matching, and low sensitivity figures. The theoretical performances under ideal and non-ideal scenarios are presented in detail. Furthermore, the proposed idea is extended to an Nth-order voltage-mode all-pass filter and a quadrature oscillator to explore some of the possible applications. PSPICE simulation results verify the theoretical claims of the presented all-pass filters. HIGHLIGHTS Two novel resistorless structures of first-order all-pass filters based on fully differential second-generation current conveyor are presented Performance of the proposed structures are thoroughly described in ideal and non-ideal scenarios Theoretically described details of the proposed structures are verified by carrying simulations on PSPICE using 180 nm CMOS technology An Nth-order all-pass filter and a quadrature oscillator are also presented as applications GRAPHICAL ABSTRACT

MOS-C Based Electronically Tuneable Current/Voltage-Mode Third Order Quadrature Oscillator and Biquadratic Filter Realization

This paper introduces a new electronically tuneable third order quadrature oscillator and biquadratic filter with MOS-C realization using all grounded passive components. Voltage-mode second order low-pass, high-pass, band-pass filters using second generation current conveyor and a current/voltage-mode third order quadrature sinusoidal oscillator using multi-output second generation current conveyor are synthesized from the proposed circuit topology. All synthesized circuits are compatible with integration and the center frequency can be electronically tuned by the gate voltage of the MOS transistors. The proposed circuits do not need any component matching condition. Oscillation condition and frequency of oscillation can be independently controlled. Workability of the proposed circuits is validated by PSPICE software using 0.18 micrometer MOSIS CMOS process parameters at ±0.9 V supply voltage. Tuneability of the oscillator is demonstrated for a tested frequency range both in voltage-mode and current-mode operations.