Jiri Hospodka

Web-Based Application for Electric Circuit Analysis

This paper presents web-based application for analysis of electric and electronic circuit. The application is based on PHP scripts and use Spice and Maple with PraCAn package as a computation engine. Continuous-time linear and nonlinear circuits as well as periodically switched linear (PSL) circuits can be analyzed. Results can be obtained in symbolic form for case of linear circuits. Description of the circuit can be entered through graphical schematic editor. It is a Java applet for netlist creation. The whole system is developed at the Department of Circuit Theory, for research and teaching support.

Design and realization of a filter bank by switched capacitor technique

The aim of this paper is to describe a method of filter bank realization using the switched capacitor (SC) technique. The analysis of steps needed for this realization is performed. The correct solution requires the IIR filter bank synthesis followed by the conversion to SC circuits. Due to simplicity only the two-channel filter bank is used. The main points of the whole design procedure and key recommendations for the realization are given. The complete design of SC circuits was performed by PraCAn package in Maple program and resulted circuit structures were simulated in WinSpice. The obtained results are in agreement with theoretical derivations

Design aspects of the SC circuits and analysis of the cross-coupled charge pump

This paper presents some real properties of the cross-coupled charge pump that is used in low-power microelectronic integrated systems operating with high voltage (FLASH, EEPROM memories). SC-circuits characterization and design aspects are firstly discussed. Theoretical analysis of the cross-coupled charge pump with accompanying equations has been done. Some real properties have been simulated by ELDO Spice and compared with these assumptions. Simulation results show discrepancy between calculation and simulated parameters due to significant pumping losses that have been discussed in detail. Discontinuity of the output voltage through input parameters is very important finding that complicates the development of the real model for design purposes.

GEEC: Graphic editor of electrical circuits

This paper presents web-based graphical schematic editor for analysis of electric and electronic circuits. It is a JavaScript application that uses Spice OPUS and Maple with PraCAn package as a computation engine. In case of linear circuits, results can be obtained in symbolic form. Continuous-time linear and nonlinear circuits as well as periodically switched linear (PSL) circuits can be analyzed. All created circuits can be exported to various file formats for greater compatibility with documentation formats and other simulation programs. The whole system is developed at the Department of Circuit Theory, for teaching support and research.

Description of the functional blocks for the cross-coupled charge pump design algorithm

This paper presents the circuit model that is used for the cross-coupled charge pump design algorithm. Symbolic description of the pump stage model as an analog functional block for high-voltage application is firstly discussed. Design process has been done by using simplified BSIM model equations assuming the long channel MOSFET. Characteristics have been verified by ELDO Spice and compared with the found relationships. Static and dynamic parameters of the subcircuit have been tested in two-stages structure by LT Spice simulator. Analysis results show the consistency between model and real circuits characteristics under given conditions. Complex model provides the reliable results for significantly smaller strange capacitances in comparision with the main pump capacitances. The model can be used for design and prediction of the pump parameters without long-time simulation process. The strong inversion region of MOSFET is expected, thus equations are correct for other MOSFET models that are used in chip design (PSP).

Guidelines on the Switch Transistors Sizing Using the Symbolic Description for the Cross-Coupled Charge Pump

This paper presents a symbolic description of the design process of the switch transistors for the cross-coupled charge pump applications. Discrete-time analog circuits are usually designed by the numerical algorithms in the professional simulator software which can be an extremely timeconsuming process in contrast to described analytical procedure. The significant part of the pumping losses is caused by the reverse current through the switch transistors due to the continuous-time voltage change on the main capacitors. The design process is based on the analytical expression of the time response characteristics of the pump stage as an analog systemwith using BSIMmodel equations. Themain benefit of the article is the analytical transistors sizing formula so that the maximum voltage gain is achieved. The diode transistor is dimensioned for the pump requirements, as the maximal pump output ripple voltage, current, etc. The characteristics of the proposed circuit have been verified by simulation in ELDO Spice. Results are valid for N-stage charge pump and also applicable for other model equations as PSP, EKV.

Design of a filter-bank by the wave digital filter technique an approach for the Chebishev bank-filter by the wave digital filter technique

This paper presents a simple procedure for design of the filter-bank with Wave digital filter (WDF). The filter-bank is constructed using Chebyshev and Inverse Chebyshev filters. Wave digital filters are derived from LC filters and consist of cascade connections of serial and parallel adapters. These adapters contains the necessary adders, multipliers and inverters. A great advantage of this procedure is that the filters in the wave digital filter-bank synthesis are obtained from the wave digital filter-bank analysis only by changing some signs in the end of delay elements.

Filters Design by Z Transformation and Pascal Matrix

In the context of the digital filter design, a great deal of research has been done to facilitate their computation. The Pascal matrix defined in [1], [2] has provided its utility in this field. In this paper we summarize the direct transformation from low-pass continuous-time transfer function H(s) to discrete-time H(z) of the bandpass and bandstop transfer functions. This algorithm uses the Pascal matrix and is constructed from the rows of a Pascal triangle. The advantage of this method is that the inverse transformation is obtained with the Pascal matrix without computing the determinant of the system, which simplifies the process to obtain the associated analog transfer function H(s) if the discrete transfer function H(z) is known. Numerical example for matrices P, P1, Q and Q1 illustrate the practical utilization of this technique.

A Virtual A/D Converter Testbench for Educational Purpose — Development and Results

A Virtual A/D Converter Testbench for Educational Purpose — Development and Results This paper deals with a new concept of virtual testing engine for analogue-to-digital converters (ADCs). The whole system consists of program procedures to extract the most important ADC errors expressed in terms of integral and differential non-linearity (INL and DNL). The developed testbench is especially suitable for educational purpose because of modular conception of the system. The proposed testing engine is implemented in Maple™, bringing an ideal possibility to make a complex system for the simulations of ADC at the virtual level as well as at the circuit level. The system is a part of a complex environment using the Servo-loop and the Histogram method, combining their features so as to obtain high level of versatility. However, in this paper we concentrate only on the results from the Servo-loop method. The Servo-loop solution proposed here employs an effective search algorithm and improves convergence properties resulting in a significant reduction of the simulation time.

Switched-current filter optimization based on evolutionary algorithms

This paper describes a way to eliminate the effect of circuit nonidealities on the magnitude frequency response of a circuit utilizing the switched-current technique. The circuit realizes a band-pass filter. The elimination is carried out by optimization based on one of evolutionary algorithms - the differential evolution. The nonidealities are nonzero on-state resistance of the switches and nonzero output conductance of the field-effect transistors implementing the current sources. It is shown that the filter with the current source transconductance values designed according to a common method for ideal components has a significantly different magnitude frequency response when the nonidealities are considered. Hence, the optimization is applied to finding suitable transconductance values so that the difference between the magnitude frequency responses of the ideal and nonideal filter is minimized.