David Matousek

Efficiency of Innovative Charge Pump versus Clock Frequency and MOSFETs Sizes

Abstract Charge pumps are circuits that produce the voltage higher than supply voltage or negative voltage. Today, charge pumps became an integral part of the electronic equipment. The integration of charge pumps directly into the system allows manufacturers to feed a complex system with many specific power requirements from a single source. However, charge pump efficiency is reduced by many phenomena. This paper is focused on the question of efficiency of proposed variant of the charge pump. In this article, the efficiency dependence on a number of stages, output current, clock frequency and MOSFETs sizes was simulated by Eldo. The aim of this study is to determine the MOSFETs sizes and theirs influence to efficiency and the output voltage. Complex optimization of the charge pump circuit will follow in further text.

High power solid state pulse compressor modeling and simulations

High power semiconductor generators of nanosecond and sub-nanosecond pulses attract an increasing interest due to their perspective application in various high power switching circuits, in control, supply or VHF systems. This paper is concentrated on an output stage of such pulse generator so called a pulse compressor based on a semiconductor diode reverse recovery switching. In the paper the compressor design and its model are described and simulations as well as experimental results are presented.

Correction of received power for Doppler measurements by FMICW radars

This electronic document is aimed at the corrections of the received power through frequency modulated interrupted continuous wave radars. These corrections are important for the correct interpretation of the target characteristics. Power corrections, described in this paper, are modified for the measurement of the Doppler shifts. Doppler shifts are calculated by the using of the two dimensional fast Fourier transform. In practical part of this paper four types of windows were compared during calculation of the two dimensional spectra. We concluded that the correction coefficients should be determined for each window individually.

Sensitivity analysis of PCDR35 radar

This conference paper is aimed at the analysis of the frequency modulated interrupted continuous wave radar (PCDR35). This radar was developed under the Institute of Atmospheric Physic Czech Academy of Sciences leadership. A primary aim of this radar is the monitoring of meteorological targets (rain cells, hail stones and other). In this paper a radar measurement of the corner reflector with the theoretical reflectivity determination are compared. In the last part of this paper an evaluation of this radar and possible modifications (classical FMCW) are described.

Comparison of positive and negative Dickson charge pump and Fibonacci charge pump

An operation of electronic equipment is dependent on a power supply. Today, a trend of only one AC/DC adapter is used for supplying an electronic system. Thus, an electronic equipment with various power supply requirements uses some internal DC/DC converters. These DC/DC converters adjust input voltage to lower or/and higher value or generate a negative voltage. The classical DC/DC converters are based on inductors or transformers. These converters are too large and suitable for a higher output power. A charge pumps are a sufficient alternative to classical DC/DC converters for a lower output power and a smaller dimension. A well-known variant of a charge pump is Dickson charge pump. The output to input voltage ratio is a directly proportional to the number of Dickson charge pump stages. Thus, the number of stages can be a relatively high for low input voltage and required high output voltage. The Fibonacci charge pump is a suitable alternative to Dickson charge pump especially for a higher output to input voltage ratio. This article describes practical circuit solution of the Fibonacci charge pump. The key properties of the Dickson and the Fibonacci pumps are compared in this article, too.

Practical aspects of realisation of negative charge pumps

A charge pump is DC/DC converter that produces a higher output voltage than power supply or generates a negative output voltage. Some variants of charge pumps work as voltage regulator, too. A charge pump is realised by capacitors, transistors and/or diodes. Therefore, some charge pumps are integrated directly to the systems that use these charge pumps. E.g. Flash or EEPROM memories are supplied from standard voltage about 3 V, but write and erase processes use a greater voltage about 12 V. This paper is concentrated on comparison of standard variant of negative charge pump with a new design. Thus, the output voltage, rise time and other parameters of these negative charge pumps are compared by simulation executed by LTspice XVII. The simulated results are verified by practical realization of charge pumps in discrete form.

New Discrete Fibonacci Charge Pump Design, Evaluation and Measurement

Abstract This paper focuses on the practical aspects of the realisation of Dickson and Fibonacci charge pumps. Standard Dickson charge pump circuit solution and new Fibonacci charge pump implementation are compared. Both charge pumps were designed and then evaluated by LTspice XVII simulations and realised in a discrete form on printed circuit board (PCB). Finally, the key parameters as the output voltage, efficiency, rise time, variable power supply and clock frequency effects were measured.

The adjoint transformation usage for correction of the attenuation of the low-pass biquad in the current mode

The second order Sallen-Key low-pass filter structures (so called biquads) in the voltage and current mode have one common disadvantage, it is a decreasing of the attenuation in the stopband. This fact is caused by losses of the amplification factor of active elements at high frequencies. Some solutions of this problem had been already published for circuits working in the voltage mode, but this problem was not satisfactorily solved for circuits working in the current mode. Therefore, this article presents one of the possible solutions of this problem for circuits working in the current mode.

The flow graph usage for the attenuation correction of the low-pass Sallen-Key biquad in the current mode

The second order Sallen-Key low-pass filter structures (so called biquads) in the voltage and the current mode have one common disadvantage. This is a decreasing of the attenuation at high frequencies, because active elements exhibit losses of the amplification. While some solutions for the voltage mode circuits have been already published, but this problem was not satisfactorily solved for circuits working in the current mode. Therefore, this article presents one of the possible solutions of this problem for circuits working in the current mode derived by graph method.

Solving BJT circuits by Nodal Voltage Method with application of diakoptical method

Bipolar transistor circuits are usually solved by their h-parameters description. However, for circuit solutions are commonly used Nodal Voltage Method based on the y-parameters. Therefore it is necessary to convert these h-parameters (hybrid parameters) to y-parameters (admittance parameters) firstly. After then the circuit is solved by hand. But the conversion of parameters is not required when diakoptical method is used. Thus this way of circuit solution is explained in this paper.