Munir A. Al-Absi

A current conveyor-based relaxation oscillator as a versatile electronic interface for capacitive and resistive sensors

A new electronic interface circuit is presented. The circuit is built around a single plus-type second-generation current conveyor (CCII+) and can be used with resistive, capacitive and resistive-capacitive sensors. Experimental results are provided.

A novel current-mode ultra low power analog CMOS four quadrant multiplier

A novel CMOS current mode analog multiplier is presented. The design is based on using MOSFET operating in subthreshold region to achieve ultra low power dissipation. The circuit is operated from ± 0.75V DC supply. The proposed circuit has been simulated using Tanner in 0.35μm TSMC CMOS process. Simulation results show that the total power dissipation is 2.3μW, total harmonic distortion is 0.7%, maximum linearity error is 0.3% and the bandwidth is 2.8MHz.

Low-voltage and low-power CMOS current-mode divider and 1/x circuit

A new low-voltage and low-power CMOS current-mode circuit that can perform divide and 1/x functions is presented. It consists of four MOSFETs biased in weak inversion. HSPICE simulation is used to confirm the functionality of the circuit. This circuit will be a useful sub-circuit for analog current mode signal processing specially medical applications.

A new CMOS current mode fast folding amplifier

Folding amplifiers are the key building blocks of folding flash analog to digital converters (ADC). Although, there are many folding amplifiers found in the literature, their transfer characteristics are either sinusoidal or triangular which causes digitization error and needs corrective measurements in folding-amplifier based ADCs. In this work, a new CMOS current-mode folding amplifier with saw-tooth transfer characteristics is proposed. The design is based on MOS operating in strong inversion. The functionality of the proposed circuit was confirmed using Tanner T-spice in TSMC 0.18μm technology. The worst case delay of the folding amplifier is found to be 25ns which is around 10 times faster than the most recent work found in the literature.

A new current-mode squaring circuit with compensation for error resulting from carrier mobility reduction

This paper presents a new current-mode squaring circuit. The design is based on MOSFETs translinear principle in strong inversion. A new compensation techniques to minimize the second order effects caused by carrier mobility reduction in short channel MOSFETs is proposed. Tanner T-spice simulation tool is used to confirm the functionality of the proposed design in 0.18μm CMOS process technology. Simulation results indicate that the maximum linearity error is 1.16 % and the power consumption is 331μW.

A novel highly accurate current mirror

A novel complementary metal-oxide semiconductor (CMOS) current mirror that can work in weak and strong inversion is proposed. The mirror is capable of accurately copying current in the nano-ampere range. The proposed scheme eliminates the DC matching error caused by the difference between drain-to-source voltages of both the input and output transistors. The proposed circuit was verified using ORCAD simulator in 0.8 μm CMOS process technology. Simulation results confirm the functionality and accuracy of the circuit.

Microtitrimetry by controlled current potentiometric titration

The classical methods of titration require large volumes of chemicals. Microtritimetry is the method of choice since it utilizes small quantities of chemicals and yields less waste compared to other conventional methods. Thus it benefits both the analytical chemists and the environment. In this communication, microtitrimetry is performed by employing the technique of differential electrolytic potentiometry for the location of the end point. Oxidation-reduction titration using platinum electrodes is described. For the first time the endpoint for a sample of 1.0 μL of 0.10 M Fe(II) has been located by titration using a solution of Ce(IV). The optimum conditions such as volume of cerium ammonium sulfate added, current applied to polarize the electrodes in case of dc controlled current potentiometric titration (CCPT). The effect of changing the percentage bias of the square wave used to polarize the electrodes on the differential peak in case of ac CCPT has been investigated. The precision of this microtitrimetric method is also reported.

A New Capacitor-Less Buck DC-DC Converter for LED Applications

In this paper, a new capacitor-less DC-DC converter is proposed to be used as a light emitting diode (LED) driver. The design is based on the utilization of the internal capacitance of the LED to replace the smoothing capacitor. LED lighting systems usually have many LEDs for better illumination that can reach multiple tens of LEDs. Such configuration can be utilized to enlarge the total internal capacitance and hence minimize the output ripple. Also, the switching frequency is selected such that a minimum ripple appears at the output. The functionality of the proposed design is confirmed experimentally and the efficiency of the driver is 85% at full load.

Frequency Independent Phase Shifter

A new simple and low cost frequency independent phase shifter is presented. The design is based on the simple op-amp phase shifter with programmable floating resistor and programmable capacitor. The phase shift can be varied using the programmable resistor. Compensation for the variation in the frequency is achieved using the programmable capacitor. Simulation results are also presented.

A CMOS Analog Cell and its applications in analog signal processing

This paper presents a core cell that can be reconfigured and combined with current mirrors to implement exponential, logarithmic, multiplier, divider and raise-to-power function circuits. The proposed circuit uses CMOS transistors operating in the strong inversion. The proposed circuits has been verified with the 0.8 µm CMOS technology by HSPICE simulations. The simulations results confirm the functionality of the proposed circuits. The proposed circuits paves the way for designing analog signal processors.