Patent ID: 6677789
Filing Date: 2004-01-13
Classification: H03L

Abstract:
A rail-to-rail linear current mode charge pump comprising:an input source current IREF; a first voltage rail VDD; a second voltage rail VSS; a first current source device coupled to said first voltage rail VDD; a first current mirroring source device for mirroring the current through said first current source device; a first switching device having ON and OFF states and responsive to a first control signal for switching between its ON and OFF states to cause said first current mirroring source device to source current to an output voltage node; a first current sink device coupled to said second voltage rail VSS; a first current mirroring sink device for mirroring the current through said first current sink device; a second switching device having ON and OFF states and responsive to a second control signal for switching between its ON and OFF states to cause said first current mirroring sink device to sink current from said output voltage node; said first current source device and said first current sink device being coupled in electrical series and forming a voltage node VCOMP therebetween; a rail-to-rail feedback network coupled between said first current source device and said first current sink device and an IREF current splitting circuit such that the current sourced to or sunk from the output voltage node is copied to the voltage node VCOMP, said voltage at the voltage node VCOMP reaching a steady state condition when the current flowing through said first current source and said first current sink devices is equal, whereby the charging or discharging of the voltage at the output voltage node is a function of the timing of the first switching device and the second switching device.