Sandisk Technologies Inc.

Gooty Sukumar Reddy

Sridhar Yadala

Potnuru Venkata Pradeep Kumar

A charge pump is connected to receive a supply voltage and a clock signal and generate an output voltage. The charge pump is connected to the supply voltage through a transistor whose gate voltage is set by a regulation voltage determined by feedback from the output voltage. The current supplied to the charge pump through this transistor is mirrored in a section that generates the clock signal, where the mirrored current is used by a current controller oscillator. This allows the pump's clock frequency to linearly track the load current, improving the pump's efficiency.

Dynamic clock period modulation scheme for variable charge pump load currents

A charge pump design suitable for generating high voltages employs multiple low voltage capacitors and low voltage transfer switches, with a limited number of high voltage devices. This is designed such that during a first clock phase, capacitors are each connected between an input voltage and ground and, during a second clock phase all the capacitors are connected in series to generate the required voltage. Both the switches (PMOS) and as well the capacitors are realized as low voltage devices. The ability to use low voltage devices can significantly reduce the area and also a reduction in current consumption relative to the usual high voltage charge pumps which uses high voltage devices.

High voltage generation using low voltage devices

Techniques are presented for improving the efficiencies of multi-stage charge pumps by reducing the amount of voltage lost across the inter-stage transfer switches of the pump through use a selective body bias. The voltage level from both branches of one stage is each supplied though a corresponding diode to the bulk connection of the transfer switch after the subsequent stage in both branches. This arrangement results in each stage providing a largely uniform amount of gain, without the usual increase of voltage drop with increasing numbers of stages.

Selective body bias for charge pump transfer switches

Methods and systems for generating voltages greater than a supply voltage are described. In some embodiments, a charge pump system may generate a boosted output voltage greater than the supply voltage using one or more charge pump stages that are arranged in series between the supply voltage and the boosted output voltage. A charge pump stage of the one or more charge pump stages may include a plurality of boosting capacitors that are arranged in series and charged to a charging voltage during a charging phase. During the charging phase, each boosting capacitor of the plurality of boosting capacitors may be charged to a fraction of the charging voltage applied across all of the plurality of boosting capacitors. After the charging phase, the plurality of boosting capacitors may be arranged in parallel and each boosting capacitor of the plurality of boosting capacitors may be boosted during a boosting phase.

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Anantapur, India

Gooty Sukumar Reddy