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.

Design of a Novel CMOS Voltage Divider

Passive linear voltage dividers are an essential part of the voltage sensing and detecting circuits. In this paper, a novel voltage divider is designed in 180nm CMOS technology and is validated with LTSpice simulations. The proposed circuit features very low steady current consumption and as a result, very little power dissipation around 200-300pW.

Design of a Novel CMOS Voltage Divider

Passive linear voltage dividers are an essential part of the voltage sensing and detecting circuits. In this paper, a novel voltage divider is designed in 180nm CMOS technology and is validated with LTSpice simulations. The proposed circuit features very low steady current consumption and as a result, very little power dissipation around 200-300pW.

Linearity Improvement of Bulk Driven Floating Gate OTA Using Cross-Bulk and Quasi-Bulk Techniques

In this paper, two highly linear OTAs are presented using a combination of three linearization techniques: floating gate, bulk driven, and source degeneration. In the first OTA, bulk driven floating gate MOSFETs are used as input transistors. The input signal given at the bulk terminals of these input transistors are in the opposite phase of the input signal provided to one of the gates of the respective floating gate MOSFET. This cross-coupling method resulted in a highly linear voltage-to-current conversion at the cost of reduced transconductance. In the second proposed OTA, this reduction in transconductance is restored by using novel quasi-bulk floating gate MOSFETs as input transistors while maintaining the improved linearity. Both the OTAs are designed and simulated using 180 nm CMOS design library and powered with [Formula: see text]0.5[Formula: see text]V dual power supply. The process variation and mismatch effects on both the OTAs are examined using corner and Monte Carlo analysis. The layouts of the proposed OTAs are also presented and workability is confirmed using post-layout simulations.

Experimental, analytical and numerical analysis of voltage distribution along the cap-and-pin insulators

This paper deals with the experimental, analytical and numerical analysis of voltage distribution along the cap-and-pin insulators. Five different insulators strings are analyzed, consisting of two, three, four, five and six cap-and-pin U40BL glass disc insulators. Experimental measurements are performed in the high voltage laboratory at the Faculty of Electrical Engineering East Sarajevo. Measurement of the voltage distribution along the disc insulators is performed by using measuring sphere gap. Analytical calculations are performed by using mathematical model which considers parasite self-capacitances of disc insulators, as well as their parasite capacitances to the earth and to the phase conductor. Calculations of the parasite capacitances values are performed and optimum values which lead to the minimum difference between measured and calculated results are suggested. Numerical analyses of the non-linear voltage distribution are performed by using electrostatic field model in software Comsol Multyphisics. 2D axisymmetric models of the cap-and-pin insulators are developed. Despite the measuring configuration is not suitable for numerical analysis, relatively good agreement between the measured results and results calculated by using specialized software are achieved.