Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
2000-04-07
2001-11-20
Kim, Jung Ho (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
C327S589000
Reexamination Certificate
active
06320456
ABSTRACT:
The invention relates to a charge pump with a supply voltage terminal and a ground terminal for generating at an output terminal an output voltage which is higher than the voltage present at the supply voltage terminal, with two complementary MOS field-effect transistors, the source-drain paths of which are connected in series between the supply voltage terminal and the ground terminal, a driving circuit for driving the two MOS field-effect transistors and a charge storage capacitor connected by one terminal to the point connecting the source-drain paths of the two MOS field-effect transistors.
Charge pumps find application in electronic circuits whenever a voltage is needed in a circuit which is higher than the available supply voltage. One such charge pump is described and illustrated in “MOS-Bauelemente in der Leistungselektronik (MOS Components in Power Electronics”) by Felix Schbrlin, published by Franzis Verlag, 1997, page 84. In this circuit a conductive connection exists between the supply voltage terminal and the output terminal via two diodes connected in series so that current is always able to flow via this connection which loads the supply voltage source even when the charge pump is not in operation. To prevent this undesired flow of current a separate switch needs to be provided to open-circuit this current.
The invention is based on the object of providing a charge pump of the aforementioned kind which requires no components other than those needed for the charge pump itself.
In accordance with the invention this object is achieved in that the charge storage capacitor is formed by the gate capacitance of a further MOS field-effect transistor, the source-drain path of which is connected at one end via a first diode to the supply voltage terminal and at the other end via a second diode to the output terminal, and the gate of which is connected to the point connecting the series arrangement of the the source-drain paths of the two complement MOS field-effect transistors.
In the charge pump in accordance with the invention the source-drain path of a further MOS field-effect transistor is inserted between the two diodes connecting the supply voltage terminal to the output terminal, this further MOS field-effect transistor acting as a switch which in the OFF state prevents any flow of current from the supply voltage terminal to the output terminal. This MOS field-effect transistor is, however, not an additional component in the charge pump since its gate capacitance simultaneously functions as the charge storage capacitor of a conventional charge pump. It is in this way that loading the supply voltage source when the charge pump is not in operation is avoided without increasing the number of components required.
REFERENCES:
patent: 5877635 (1999-03-01), Lin
patent: 5962887 (1999-10-01), Manning et al.
Kempler William B.
Kim Jung Ho
Telecky , Jr. Frederick J.
Texas Instruments Deutschland GmbH
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