Regulation of the output voltage of a voltage multiplier

Abstract

The regulation of the output voltage of a voltage multiplier driven by a ring oscillator, an inverter of which is substituted by a NOR gate for providing a terminal through which stopping the oscillation, is effected by controlling the oscillation frequency in function of the current delivered by the voltage multiplier by means of a transistor T1 working as a current generator connected in series with a regulating chain of series-connected diodes by biasing the gate of the transistor with a constant voltage Vref, thus imposing a reference current Iref through the transistor. The voltage signal across the transistor is fed to the input of a first inverter with a preset triggering threshold and the output signal of the inverter is fed through an amplifying and phase-regenerating stage to said terminal for stopping the oscillation of said NOR gate of the ring oscillator. When the discharge current through the regulating chain becomes greater than the imposed current Iref, across the transistor T1 a voltage signal develops which, beyond a certain threshold, determines the switching of the inverter and, through the amplifying and phase-regenerating stage, causes a stop of the oscillation which resumes only when conduction through the regulating chain stops. At steady state the oscillation frequency will result controlled so as to maintain constant the output voltage of the voltage multiplier and to limit the discharge current through the regulating chain thus limiting power consumption.

What we claim is: .[.1. A circuit for regulating the output voltage of a system for multiplying a supply voltage comprising a multistage voltage multiplier circuit, wherein each stage is formed essentially by a diode and a capacitor connected so as to transfer electric charge in a single direction from a supply terminal to an output capacitor to which an output terminal of the voltage multiplier is connected, an oscillator capable of generating two driving signals with a 180° phase difference between each other for driving the charge transfer from any stage to a successive stage of said multistage multiplier and having an input terminal (C) for applying an oscillation stop signal, and a chain of diodes or of diode-equivalent structures functionally connected in series between said output terminal of the voltage multiplier and ground for regulating the output voltage, characterized by comprising 
     
        threshold of said trigger circuit. .Iaddend..Iadd.4.  The circuit of claim 3 wherein said constant current generator is a transistor..Iaddend. .Iadd.5. The circuit of claim 4 wherein said transistor is a field effect transistor having a source-drain current path connected between said voltage regulator and ground, and a gate connected to a reference potential..Iaddend. .Iadd.6. The circuit of claim 3 wherein said trigger circuit comprises an inverter and a Schmitt trigger..Iaddend. .Iadd.7. The circuit of claim 6 wherein said trigger circuit regenerates the phase of said first signal in said oscillation interrupt signal..Iaddend. .Iadd.8. The circuit of claim 3 wherein said voltage regulator comprises a chain of diodes..Iaddend. .Iadd.9. The circuit of claim 8 wherein said diodes are diode-connected transistors..Iaddend. .Iadd.10. The circuit of claim 9 wherein said diode-connected transistors are p-channel transistors..Iaddend. .Iadd.11. The circuit of claim 9 wherein said diode-connected transistors are Zener diodes..Iaddend. .Iadd.12. The circuit of claim 9 wherein said diode-connected transistors are parasitic transistors..Iaddend. .Iadd.13. The circuit of claim 3 wherein said voltage multiplier is a multistage circuit each comprising a diode and capacitor connected to transfer a charge from an input to an output, and wherein said oscillator provides a plurality of phased driving signals connected to drive the charge through the stages of said voltage multiplier..Iaddend. .Iadd.14. The circuit of claim 3 wherein said oscillator is a ring oscillator..Iaddend. .Iadd.15. The circuit of claim 14 wherein said ring oscillator comprises two outputs phased 180° apart..Iaddend. .Iadd.16. The circuit of claim 14 wherein said ring oscillator comprises a NOR gate providing an invertor function, an input of said NOR gate providing said terminal for receiving an oscillation interrupt signal..Iaddend.