Design of precision voltage-controlled constant current source with low power dissipation single-supply

In this paper a low power single-supply precision voltage-controlled constant current source is designed. Firstly the schematic diagram of the circuit is given, and then the transfer properties of the circuit are deduced according to the equivalent circuit model, finally the equivalent output characteristic impedance of the circuit is analyzed in detail. Simulation result shows that the stability of the output current is high and the relative error of the current fluctuation under the load of 0-200 and the frequency of 220 kHz is less than 1.6%. A rapid moisture tester for meat developed by the author employs the constant current circuit designed in this paper and has got popular applications.