ANALYSIS AND DESIGN OF VOLTAGE-CONTROLLED CURRENT SOURCES

What is it about?

The paper presents the structure and the principle of operation of the "Improved" Howland Current Pumps (or voltage-controlled current sources – VCCSs for a grounded load). In particular, under review is the VCCS employing power operational amplifier (op amp) and the VCCS using low power op amp and an additional power transistor, extending working dynamic range. Based on analysis of the operational principle, the equations for transfer functions of both circuits and formulas for the related dynamic electrical parameters are obtained. Moreover, using these formulas a design procedure is developed and recommendations for simulation modelling are given. The efficiency of the proposed procedure is verified by simulation modelling and experimental testing of sample electronic circuits of VCCSs.

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Why is it important?

A design procedure of VCCSs for a grounded load ("Improved" Howland Current Pumps) has been presented. The proposed methodology integrates the traditional engineering design calculations with the possibilities of the PSpice simulations. The created approach can be useful for analysis and design of VCCSs for a grounded load employing in various analogue and mixed-signal circuits and systems.